I dont think everyone should get 75 coins then, but a share of the 75 coins. Maybe bump it up a little, because at the moment more than 75 coins are handed out in a minute. So if you give 300 for a minute shared by participants, that could be okay, I guess?
This is reasonable, we'll try to implement it. Anyway, looking at the timestamp of the last problems solved there is a rate slower than you may think:
http://www.diracoin.org/BrainCypher/AllBrainCypher