I have a 03 asx that has seen some abuse. I am 250lbs and this is my third season on this frame. I use this bike for local free ride trails and whistler trips.
Here are my major issues with this frame:
During my three years with the asx I have broken two swing arms near the dropouts. Yeti promptly sent me replacements under warranty. The last swing arm Yeti sent me was a modified 05 version. The dropouts are now reinforced and I have not had any issues yet (> 1.5 seasons).
The swing arm could stand to have more lateral stiffness, but that would undoubtedly add more sprung weight.
The frame holes for the 7in travel setting have ovalized, but the newer versions have used thicker aluminum in this spot to prevent such wear.
I think the new asx is perfect for freeride, and if I had to replace my 03 asx today, I would get the new asx.