I've not heard of the carriers distorting but from a personal viewpoint they are the most likely thing for an amateur mechanic to break. When I got my car I was lucky in having a local Lotus specialist who was also a personal friend and he spent many lunchtimes telling me what NOT to do !
The alloy is soft and careless pressing in or out of bearings will damage the machined surfaces & hence you get what looks like bearing play. I was told to assemble using Loctite "Bearing Fit" which is a high strength, large gap filling assembly fluid. Likewise to fit the hubs with the same stuff, coating the splines until it runs out at the end of the hub before tightening the hub nut "as tight as you can with a breaker bar, just forget trying to measure the torque figure, stand on it".
This was because there were originally problems with them loosening in service and this seemed to be the way the problem was solved. And as previously commented in the thread, worn splines or a loosening hub nut all give similar effects at the wheel.
But this meant you needed to heat the hub & housing to soften the Loctite before you could dismantle them, without heat I'm sure you'd stand a good chance of damaging something. And if you don't know about the Loctite (and the average mechanic isn't likely to) then you can see how so many get "worn"
I think the castings were all the same but there were machining mods along the way. The early ones used a strange 31mm smaller bearing, rationalised to a 30mm one for the TC and then to two identical bearings on the Special (they used the larger one from the S2/TC). I did think about converting mine to the larger bearings but Chris (the Lotus specialist) said it wouldn't make that much difference in his opinion as they seemed to have similar failure rates. He was more concerned about shimming the driveshafts & condition of the UJs.
Brian