I agree. I ran out of my aurifil and had some mettler sitting around, so I started using that. I'm not a fan because I noticed a significant increase in lint. The aurifil has almost none compared to what I'm getting off the mettler. I have also used superior so fine and I like that a lot. I recently ordered some superior king tut (should be here by Friday), and I've heard good things about that and I'm looking forward to trying it out this weekend.
One other observation, is that the mettler seems to be thicker and stiffer. Even though I always buy 50 weight, the mettler feels thicker, and I seem to have more issues with thread breaking while FMQ (full disclosure, that could be, and probably is, user error).
If it helps, I have a bernina record 930.