Very high courage & protection instinct means these dobermann have been selected (for generations) and have a natural (genetic) instinct to protect you and your property - and the courage to follow through if , for example, "barking at the window" does not deter an intruder. 

Middle Sharpness is the ideal. Sharpness refers to response to stimulus and is linked to nerve fiber and defensive aggression.  The middle sharp dog does not react to a threat that is not there.  An overly sharp dog is NOT a good working dog & represents a potential liability as a pet (rather than a reliable protector). 

Very high hardness means a dog can be shaped in extremely demanding/high levels of training but it also means corrections can have less effect. 
Some Blitzkrieger combinations are made for clients who prefer a lesser degree of hardness, more biddability in obedience, agility, etc... and although clients are informed if this selection applies to a combination,  please keep in mind that hardness is a relative term and all Blitzkrieger dobermann do have hardness.

Working lines have high drive which provides them with superior motivation to work = sport/obedience/agility/  etc... 
(See "Make a commitment to a higher level of training" below).   This high drive must be accompanied by good nerve (tested in schutzhund by gunfire, tracking, etc..) which also ensures that, as  "pets", they are least likely to "spook" when the unexpected happens (i.e:  when a car backfires, etc..).   Excellent nerve fiber also means they have the ability to turn off their high drives and be very calm (on/off switch) but they do require some (daily) outlet for this drive. 

I know, from many years experience (combinations in Germany and my own), they are "Happy Dogs" = EXTREMELY affectionate & intelligent companions.   Many times they have demonstrated their ability to respond to a situation with outstanding discernment (without prior training therein).   But perhaps the most often repeated, outstanding characteristic of these dobermann can be summed up in the word "CONFIDENCE".

A "responsible owner" will:
*Socialize their puppy.  Regardless of the confidence bestowed by genetics, all young dogs need to gain experience by being thoroughly introduced to the "world" outside their home.  The list (people/places/sounds/situations/other animals/etc...) is almost endless and you cannot do too much of this. 
*Set aside time time each day to provide exercise (playing/ training or walking, etc...).  This is VERY important, not only in terms of bonding and/or imprinting but, providing this "on" time (energy outlet), means your dobermann will more likely be willing/able to switch their energy "off".   (A consistant schedule helps.) This might only be a long, daily walk but, if you are too busy to do this, you are too busy to own one of my dobermann!      Of course young pups have more energy and I recommend providing an area (i.e: 20x10 run with dog house) where your pup can "be a pup" without getting into trouble while you are resting or tending to other business.   If you start when your pup is young and make this a fun place (complete with rawhide bone for chewing, etc....) your pup is not likely to resent it.  This also applies to crates, which are useful with young pups at night - but not recommended to include long periods in the day.
*Make a commitment to a higher level of training.   This means learning how to utilize your dobermann's high (prey/ball/food) drives to motivate them to do what your want.  If you do this, they will work long after their lower drive relatives have headed for the couch.  I highly recommend books, such as: "Schutzhund Obedience - Training in Drive" with Gottfried Dildei by Sheila Booth as excellent information source for those interested in working (obedience) with any high drive/hard dog, even if you never contemplate schutzhund! 
Those owners who prefer to rely soley on leash corrections would be far more successful with a soft, low drive dog! 
NOTE:  Soft, lower drive dogs form the majority of participants in "pet" type obedience classes. The type of obedience training in these classes is usually geared to suit this type of dog and rarely reflects the same obedience training you will encounter at a schutzhund club where high drive, hard dogs are the norm.  At a schutzhund club you will learn to enhance/channel your dogs drives  (a high drive dog will work for a ball/tug but with less precision in the beginning) and (at a later age) you will learn how to administer well timed, strong corrections combined with motivation from the drives you have enhanced/shaped.   The end result allows you to shape high drive, hard dogs at a VERY high level of precision and control in tracking, obedience and bitework (Lower drive, soft dogs are not suited to schutzhund because they cannot endure these higher levels of shaping. They simply do not have the will {drives} to work at this level.) 
High prey drive in young pups means they instinctively desire to playfully chase/bite what moves.   For this reason, they should not be left unattended with young children.  Providing a suitable outlet (Playtime, training/tug/ragwork, even a rawhide bone) is essential and enables you to shape drives.  There is absolutely NO point in owning a high drive dog if you are constantly diminishing those drives! 
*Be responsible for the safety of their dobermann and for the safety of other people/animals.  I keep all pups and even my older dobermann on a long line (or train in an enclosed area) until control work is proven under distractions.   Blitzkrieger Kennel does NOT recommend novices engage in any bitework training outsite of Schutzhund!   This type of training requires an experienced handler and a certified trainer. 

A responsible Breeder will work with you to select a pup best suited to you/your requirements so it is crucial to provide them with as much information (about yourself, your environment/experience with dogs/training goals/etc..) as possible. 
Dobermann from "Working (Schutzhund/Police) lines" are selected/bred for character traits that are admired & honored - on or off the schutzhund field.   They are not for everyone but they are outstanding Companions/Protectors!