I have been on both sides of the fence with trying to train a "less than ideal" dog for a SAR discipline. I can tell you that as the owner/handler of a dog who was really not suited for what I wanted to do, I went through all the usual arguments that are posed by someone who says "don't tell me to get a different breed". This was the breed I loved. I had the dog before I had the itch to try SAR. That is the way it usually is with SAR dog handlers. I decided to give it a shot. I had a lot of wonderful daydreams about how we were going to forge a beautiful partnership and in all my daydreams we of course ALWAYS made the find. The reality is that my dog had a wonderful nose and could cut through scent pools with ease, but she didn't care to work. She would work for a few minutes and then clown around, wanting her ball reward. She was older, five years old, and she didn't come from a working background. Sure, she could do it, physically, but that wasn't what I originally got her for, and what she does best is be a funny and smart-as-a-whip companion. She wasn't "there" mentally, her mind was elsewhere. She competes in obedience, and when she feels like it she does really well. A lot of times she doesn't feel like it. She may one day compete in AKC tracking, but that is now the extent of her scent work. Oh, and she impresses the kids in the local parks by finding the balls they lose in the ivy.
One of the biggest things I learned as I was struggling to train her was that my refusal to give up didn't just affect me. I also needed the attention of experienced team members, attention that was also being demanded by other novices. Novices who had dogs that were, frankly, more suited to the work. SAR isn't an individual undertaking, especially if you are training your first SAR dog. It is REEEEEALY hard. You need the help of experienced handlers. What happened on my team was that the other members gradually pulled away and let me figure it out myself.