Doberman myths
The Doberman is without a doubt one of breeds that is the most subject to unfair and discriminatory myths. Whether it is because of its working background, Hollywood movies or other factors, people – who most often have never owned or had direct contact with one – have relentlessly perpetuated an unfounded negative public image of the Doberman breed through the year.
This unending work of fiction includes, but is not limited to:
The Doberman is one of the most difficult dog breeds to train

This could not be any less true. But the myth still exists for a very simple reason: the people who perpetuate it have no idea how to train a dog.
The Doberman ranks amongst the most intelligent of dog breeds in experimental studies and expert evaluations regarding obedience and trainability, along with the Border Collie, Golden Retriever, Poodle, German Sheperd and Shetland Sheepdog breeds. As a result, unless you do not possess sufficient knowledge to train dogs, the Doberman is by far one of the most trainable breeds.
The reality is that if you do not possess sufficient knowledge to train dogs, a Doberman will quickly outsmart you. This will probably lead you to believe it is hard to train.
The "King Doberman" is the largest Doberman breed there is

Let us all be reassured: there is no such thing as a "King Doberman" breed. Never has been registered by any National Kennel authority, and never will be. No King Doberman will come and get you while you sleep. No King Doberman will hunt your kids down.
At some point in time, someone, somewhere thought it would be a good idea to have a "larger-than-average" Doberman. And so, that someone based his breeding program for several generations on one single priority: size. Not health, not temperament: just size. And at some point in time, someone, somewhere thought it would be clever to call such a thing "King Doberman".
Never mind the fact that such a breeding program did not consider health and temperament as a prime priority instead of size: most veterinarians will acknowledge that the oversize versions of each breed are usually more prone to health issues (joints, bones, arthritis, etc.) and have shorter longevity.
Not to mention you may end up with a mix breed, as several of those lines of "larger-than-average" Dobermans were bred with Great Danes many generations back, something which can only be determined with a Breed DNA Testing.
It is usually wise to deal with registered breeders who respect the breed standard and have a history of puppies falling within that standard range as they grow old.
The Doberman brains become too large for its skull which drives it to attack its owner

As any physician, veterinarian - or thinking person - will tell you, when the cranium stops growing, so do the brains. This applies for all breeds of dog - and mammals for that matter.
The only reasons a Doberman would purposefully attack a human being are:
1) it is being attacked and is defending itself, or;
2) it has been trained to behave that way.
Most Dobermans have many health issues and die young

Change and add a few words to this myth, and you will have a drastically different statement, and one that is true. That statement would sound something like:
"The Doberman breed is prone to a few health issues that are unlikely to affect a breeder's litters if the lineage was appropriately health-tested."
Since registered breeders adhere to a Code of Ethics which includes health testing of both parents, the statistical probability of any of those health issues being passed on and surfacing is significantly reduced. Hence the importance of dealing with ethical and responsible breeders.
As he conducts appropriate health testing as part of his breeding program, a breeder also ensures greater longevity for his bloodlines by reducing the occurrence of vWD, DCM and CHD, among others.
Dobermans are among the most aggressive breeds and are more likely to attack unprovoked

Pitbulls, Rottweilers and Dobermans are NOT among the most aggressive dogs. They are among the most powerful dogs. As such, ill-intentioned people may unfortunately raise and train them to take part in unethical security work or illegal fighting, which perpetuates the "naturally aggressive" myth.
Any dog - including a Chihuahua or a French Bulldog - can be trained to be aggressive. The difference is that some dogs - when trained by humans to be aggressive - will have a higher potential to inflict damage, which again, perpetuates the "naturally aggressive" myth.
The only reasons a Doberman would purposefully attack a human being are:
1) it is being attacked and is defending itself, or;
2) it has been trained to behave that way.
There are health and longevity differences between European and American Dobermans

Although much has been - and is still being - said and written on this never-ending topic of conversation, no scientific study has ever been produced by a recognized authority to suggest that European or American bloodlines are more or less prone to health issues, or enjoy longer or lesser longevity. (if you are aware of one, we would appreciate if you could kindly share it with us)
At the end of the day, the proof is in the pudding: you will either have to decide to take a breeder's word for it, or thoroughly investigate his past litters and research how long each Doberman has lived. As you can imagine, the latter will prove to be utterly time-consuming and expensive.
Other options include online research, chat rooms reviews and blogs' investigation to assess what people are saying about the breeder - which is by no means a more scientific method than taking the breeder's word.
The Doberman breed is mostly bred to be a guard/security dog

Although highly capable of learning and performing most of these tasks because of its top-level intelligence, strength and athleticism – and historically linked to the more physical jobs known to working dogs – the Doberman is no-longer typically bred to be a working dog.
Originally “engineered” around intelligence, strength and athleticism and bred to “scare & protect” 125 years ago, the overwhelming majority of Doberman breeders have grown to predominantly model their breeding program since World War II around health as well as positive temperament and behavior. Of course, you may still see some Dobermans acting as the odd police and guard dog, but this is becoming less common.
Today’s Doberman is clearly more of a loving and loyal household companion than the million-dollar home guard dog it is sometimes portrayed to be by Hollywood.
The temperament can be selected when buying a Doberman puppy

Choosing between a hyper or calm Doberman puppy is not to be confused with choosing between a mild or medium spicy Thai fried rice, or between a red or black Ferrari.
It is true that some general personality traits maybe very well come out through early interaction with the rest of the litter between one and three months of age. However, your Doberman's long-term temperament does not come "pre-programmed" with lineage and will mostly be established and reinforced by the way the puppy is raised, trained and disciplined in its new household before it turns one year old.
Make no mistake about it: as a new home, you have complete control over and responsibility of your Doberman's temperament. Whether you decide to train it yourself or get professional help to steer the process is entirely up to you.