it is at least a good question, and there are many different opions about it in the forums. So probadly you will get quite a lot good comment, but will be still confused about it.
I am also not sure about it, i know some good SB Centers, where i am not convinced that the extra salary is worth it. but i got one SB 11 eleven Center, which is normally a crappy number cause it is high enough to be important for salary and to low to matchup the IS of the opposition. He normally ends betwen 1,5 and 2 Blocks, when ou consider that the also affect the same amount of shots sgnificant with it, and C usually don't take that many shot, it is not unimportant.
So when the U21 coach, is with me, i like to go for more SB and nearly no ID training for my new U21 Center.