I see you are in Buffalo - not sure where you will be adopting the new dog from, but perhaps Sampson could help choose the dog - I am not saying puppy because he might like an older buddy - you never know. With rescue we always have the dogs meet and see how they do - there is usually a pretty clear message one way or another - though sometimes it's just "meh" which is okay too!
Of course, the owners are not always the best judge of it because they see a dog they want badly and try to shove that square peg in round hole - and end up with a bad situation - so you want to have a few different eyes on the dogs' meetings. You do say "as you raised and trained Sampson" which is only since you got him at 10 months - so there is a lot more to go there, but if they are the ones getting the dog, and they are the ones taking care of it, I am guessing that means that the whole family will be involved in its care.
I believe there are 2 Karen Pryor trained clicker trainers in the Buffalo area, and there is another (I am just copying and pasting one of my old posts here):
I do not know this trainer personally - I did a search on the CPDT website for find a trainer: http://www.purrfectpawsabc.com/Staff.htm
But she has 2 Dutch Shepherds and more than a trainer who can work with Shepherds, I look for trainers that work with breeds that are harder to train and she does have a JRT/Bulldog mix - yeep.
I would contact and go out to observe, and do that with some other places as well, and see what you think. I do appreciate her philosophy as it is written and always like to see it in action if I can before bringing my dog in.
ETA - Is Sampson adopted/are you actually adopting as in a shelter/rescue?
Telling whoever you are getting the dog from what you told us will be helpful to them.
Editing again - a female MIGHT be the better bet, personalities and temperaments matching will matter most.