Re: why do people use pools with fees when the cost to switch is nil?
You can't be sure you are getting more from 0% fee pool than from 2% fee pool without comparison on a lengthy intervals. The pool operator can skim blocks (there is no free launch 
, pool operator can implement protocol inefficiently and give identical getworks to multiple clients, pool can get a lot of invalid blocks due to bad connection to bitcoin network, pool can get a lot of stale shares.
Unfortunately, to this time nobody did a proper comparison of pools according to their published statistic, so you can only use your intuition to choose one.
This is a good point as well, and something I have considered to a great extent. It's another reason I like the larger pools. Less variance means you can more easily compare daily BTC rates., pool operator can implement protocol inefficiently and give identical getworks to multiple clients, pool can get a lot of invalid blocks due to bad connection to bitcoin network, pool can get a lot of stale shares.Unfortunately, to this time nobody did a proper comparison of pools according to their published statistic, so you can only use your intuition to choose one.