Can't see any reason why not to use ECS. Over the past 8 years I've build a couple of ECS based systems, all at the low end of the market (read: cheapest AMD-motherboard without onboard video available) and all five are still up and running without trouble. I've read about ECS troubles but most came down due to trying to run the boards beyond specification speeds (extreem overclocking). You can't really fault ECS on that, afterall, if you want Ferrari performance you won't buy a Fiat Punto and try to stretch its performance to match the Ferrari's.
Just for the fun, you could build your PC and can proudly tell it has ECS and AAA. ECS for the mainboard, AAA being AMD, ATi and Antec.
