Well, actually I was talking about individual shares. Of course that's a few 100 MiB for longer rounds. But it would be enough to keep them online for 10 days or so. And they compress really well. The individual shares are needed to check if the scoring works. And I think the pool will change to difficulty-2-shares somewhen anyway, that would again half the size.

Of course that should not hinder you to also provide nice aggregated statistics. 

[edit:] Maybe I could volunteer then to write some python or perl script that does some statistics on the dump file if there are requests.