It makes more sense, then, that the rules be "contribute what you are willing to contribute, and be compensated according to what others are willing to pay". Which is market exchange.
I was just commenting on the "it's not really exploitation". It probably is if you don't contribute what you can. I don't adress any of the other issues with this sort of pool.
But if you have 3 GPU and 1 P3 (all idle), and you contribute the P3, you're not contributing what you can. If the GPUs are used for folding@home, then you only have the P3 to contribute, and hence not exploiting.
IMHO.
I'm a market liberal kind of guy myself, so I don't think this kind of pool would work either unless it's a very tight group doing it. Like a family or similar.