So I guess to fine tune the question, does nage's feeling they get from spreading fingers negate/outweigh the danger of breaking them? You may have to speed up your training to find out.
aikido perspective: I'm inclined to listen to Ueshiba, Takeda, Sagawa and Shioda over some random instructor.
fighting perspective: I"m not sure it's the right thing to be asking aikidoka about fighting, but I think the concerns are overblown. As I said, I don't recall seeing MMA fighters or judoka going out of their way to protect their fingers and I don't recall a fight being stopped because a guy broke a finger and couldn't continue. It's just a finger, rub some dirt on it.