The MA3 has a reputation, deserved or not, of cracking at the eyelets. Mavic has replaced it in 2006. I just built my brother a new rear wheel with his old Campy hub and an Ma3, and I hope this doesn't happen to him. He's only 160# though.

His old rim is crazily cracked - at almost every eyelet on the drive side, cracks are starting to propogate through the aluminum. But his old rim is an aero-profile rim, and cracks developing in that sort of rim don't "lift" away, the way that a box-section rim like the MA3 will do. Which means, my brother could ride this old rim for 1000 miles after cracks started, but with the MA3 (or the MA40, which I cracked this summer on my bike) you should replace it immediately.