I am considering doing this with one of the next coins I add, with PPS as the payout method. You would submit shares in that currency and get paid per share in LTC.
However, I would not be able to do this fee-free, there will likely have to be a 2-3% PPS fee (which certain members would be exempt from) as well as some kind of exchange fee to mitigate my risk in exchanging a potentially volatile currency for a stable one. This would free users from having to maintain so many wallets and not having to worry about exchanging their coins. If it works out well with the new coin I would likely move most of the coins on the pool to the new payout method. Stay tuned.
I'ld love to see this somewhere down the line

I wouldn't mind the fees, because we pay fees in exchanging for LTC anyway

I guess you'ld convert all users' balances like once every 24 hours, so you don't need to initiate too many small transactions? Plus, it also makes it a bit safer for you, because everyone gets paid at the current rate of that moment, so there can be no discussion

Only issue would be that your sell order of a certain coin would be larger than a buy order, but that remains to be seen
