Someone made a similar argument in another thread, and I can't help but wonder: if distributed computing is that decisively disadvantageous vs. cluster computing, why is it still going on?
The primary value of distributed computing projects is public awareness not the crunching itself. Ultimately the goal of awareness is community involvement.
However in most cases, opening up your checkbook is actually a more useful way to get involved than crunching work units since cash can be used in many different ways. As we have touched on the buying power at a institutional level is far better than at the individual consumer level.
For smaller and newer projects, I think there's a case for distributed computing projects, simply to get the issue in the public eye to a certain segment of the population who might be unaware of such matters.
There's a cost and overhead associated with all of these distributed computing programs. They aren't free. Could the money used to collect data, hire staff, distribute, process, analyze be used more strategically for other things? At the end of the day, these are all fundamentally marketing projects to increase awareness.
It's up to each organization to review their distributed computing project periodically and evaluate whether or not it fits in with the overall mission. SETI@home is one project that has terminated public involvement at this time. There's no one single approach for every organization that applies at the same moment for everyone.
But without a doubt, these distributed computing projects are a tiny fraction of the overall budget of the larger organization behind the effort. In the end, a monetary donation (or fully appreciated equities) goes farther because the funds can be allocated to a far greater number of usage cases.
Again, it's hard to ignore the tax implications from a consumer standpoint. If I give American Cancer Society one dollar in cash, I can claim some of that as a deduction. If I give American Cancer Society one dollar in electricity at residential rates (including hardware depreciation), I can't claim any of that.
Your tax advisor isn't going to ask you how many work units you crunched. But they will ask you if you made any charitable contributions. The federal and state governments recognize those contributions.
Maybe you get a lot of satisfaction seeing your BOINC work unit counter increment. Pat yourself on the back and give yourself an "attaboy". If you like that more than seeing a $100 check cashed in your checking account, stick with the distributed computing. Or do both if you like.