if this person wanted a personal protection dog i doubt that they would choose a ddb in the first place as it is not suited for this task as well as many others... but will it defend its owner ?? my answer is most definitly yes. are they all couch potato's =no Hd is very common in many large breeds and all breeds of mastiff Skin problems. my ddB has no hip problem's shes been xrayed she has dry skin in the winter cureable with oatmeal baths she will protect me no matter what. she does like the couch.. :) she barely snores. has no other breathing problems im aware of. she can run around outside all day long but she likes to come inside and lick me after a hour or 2 then she wants back out. she is extremely well trained and very very smart and willing to be trained. if i want her to run with me she will until she is completely worn out she can run around for 30-40 minutes nonstop playing with other dogs /walking /ect before she gets tired and takes a breather i belive the original poster needs to enlighten us with what their idea of protector is. or a beautiful sweet animal that will be glad to defend its owner/family in a pinch. also getting back to the original post ... yes there is a lot of variation in this breed the ddb does need a lot of exercise most think it does not due to is lazyness when inside. but when outside the ddb will be much more active. those who just walk their ddb need to consider taking it to a free run park or to the country to get the exercise it truely needs. also most breeders have taken most of the aggressiveness out of this animal others have not but most of the ones you will see are the calmer mellower versions. as the old style breed is all but nonexhistant. for some a ddb may be a good choice for a family protector. for a ppd no way too many issues but it could be done, however it would not be my first choice for a ppd at all. they are even tempered animals around your children and very protective (given attention/love). if you dont give it attention though and it only see's you when it gets fed it may be your hand it bites. for a junkyard dog or a backyard ornament this dog is a very horrible choice. honestly I think ddb is a serious protector very mellow animal. if that makes it a couch potato. then so be it but it also is still a very serious protector its protection instincts are still very real. I dont think I know anyone that wants to be on the recieving end of an angry ddb bite. and I dont think Ii know anyone that my dog will not bite if she felt I was in danger.