perhaps the WebMonkey scoring system might be a better "fit"
instead of applying weight to shares and then devaluing said weight as the round goes on, a simpler, lighter approach:
based soley on time in round.
100% time spent mining in round = 100% of miner's estimated payout.
10% time spent mining in round = 10% of miner's estimated payout.
not only does this discourage people from leaving during the "1st half" of the round, but also discourages entering during the "2nd half" of the round.
now, i realise that is very simple (and very light) but a percent here or there could be tweaked to allow a tiny variance of miner reboot or even server outtage.
(round = round - outtage) BEFORE calculation of payout.
* WebMonkey crawls back into his way out of touch hermit hole and turns on the 80s pop music
'monkey