I'm testing coinsolver vs WafflePool on a single card too ....
24 h of 310 khs generated 0.002 BTC on coinsolver
12 h on wafflepool 0.00078 BTC ...
thing is on waffle I get only 1% rejected share whereas in coinsolver is way high ... about 15% or more varying ... maybe due to no vardiff on coinsolver
Same card or different cards? The hard part is leaving it there, stable, long enough to get a good reading (1-2 weeks I'd say).
Some of the profit switching pools will actually count rejects (usually only 1 round old rejects though). Because of this, you might want to ensure that you don't use the --no-submit-stale flag.