Okay, so the thread I started has disappeared and I wanted to give you guys an update so here it is + original story:
When I had Ksyrium SLs on my bike, all was good, no buckling, no out-of-true dramas, nothing! Gorgeous wheels.
Updated to ksyrium ESs recently and I've kicked the rear out of true twice. So I'm getting suspicious. I call a guy I know here in sydney who's ex-mavic and he says - well, you SHOULDN'T be kicking it out (I weigh 226 lbs) and he asks me whether I'm a super agressive out-of-the-saddle sprinter. I say no, not really so he's going to check out the rim and see what he can do. (He's a wheel building specialist). So fingers crossed he can work some magic over it 'cause I really do like them.
He also said that whilst Mavic designed these rims for 187 lbs riders, the worse I can do to them is wear them out quicker. Long and short of it is, if they're not trued properly they'll get kicked out again.