I was only getting about 8 Mh/s effective hashrate at the pool with r24 as opposed to 10.5 Mh/s with r23. I'll be sticking with r23 for now.
those hashrates are superb ... but as sp works on the miner and optimizations - there is bound to be some mishaps along the way ...
im still runing the latest git pull - and will stay on it for now - to test stability also ...

i too have issues with extranonce2 errors though ... westhash is the main one ... yaamp is down at the moment - but was not getting too many errors there ...
have you overclocked the cards to get those hashrates? ... if so - how? ... assuming you are using linux too as per your post ...
tanx ...
#crysx
Those hashrates are for two 750Ti's.. sorry if I wasn't clear about that!
10.5M/2 = 5250 khash/s effective at the pool (YAAMP) for quark. I get about 5550 +/- 50 khash/s reported from the miner itself.