I recently "down-grade" (Sis735 is much cheaper) my system from Epox KT266 mobo to Chaintech Sis735.
Stability-wise, they both pretty good.
Speed-wise, Sis735 perform little better. (actually noticable when playing high resolution game)
However, ECS and Chaintech mobo can't OC at all!!!!!!!!!!!!!
I could easily run my Morgan Duron at 133X9 w/ KT266
but I stuck w/ 100X10 w/ Sis735.
hmmm........................