I think this is dangerous. It means a 100% guaranteed "better than average" luck to anyone who mines on eligius. If everyone was 100% rational (and not pool hopping), they'd stop mining at their current pool and jump to eligius instantly as soon as payouts are increased. Until, at some point in the future, eligius has 100BTC funds and reduces payouts. Chances are the situation won't improve and payouts are lowered even more after the next block. Now everyone should go to a score-based pool or ArsBitcoin with SMPPS.

I'm not mining at eligius, but I'd say: Keep the buffer as high as possible, until it's pretty sure (because of difficulty changes) that the buffer will be sufficient even with pretty bad luck. Then distribute some of the buffer, but distribute based on past mining work, not on the future. Look at ArsBitcoin, the buffer is at almost 600BTC there, while only 1000BTC have been paid out (1600 earned, 1000 paid). It's a good state for a SMPPS pool, because the miners can be sure to get the PPS payout for at least a few days.