I'll warrant that the F@H people can cheat the system (destroying all value) if they wanted to. But 1) why would they want to do that? and 2) that's the price of doing business--there's no practical way around centralization of work distribution and verification in this context.
I don't know what your system is like and I understand if you want to keep it under wraps for now, but based on my naive understanding there are lots of problems:
- At times when F@H is down and there are no rewards, why would anyone waste power to confirm transactions?
- What if someone greedy at F@H rigs stuff to make it look like an address belong to himself did work?
- What if the F@H project is terminated? I assume more than one project will be involved, but if something happens to a major one it could create a shock.
- Who decides what projects are included? What prevents someone for gaining free computing for his for-profit project?
- What happens when Bitcoin is x1000000 times the size of F@H and you have the whole world's economy relying on a few obscure charities?
Unless you have some magic solution, I think you're completely missing the point of why Bitcoin's decentralization is so important. The solution to the "wastefullness" of hashing should be in the form of allowing more security with less resources (eg branch selection based on proof-of-stake and bitcoin days destroyed).