We used Extrusion for our frame (#64 Gila Monsters) in 2002. We survived our first regional in Seattle without needing any repairs to the frame, but we needed to replace the front after the LA regional...
Some things to consider though.
a) We seeded first and with team 60 and 330 we ended up winning (so we played LOTS of competitive matches)
b) Mike Rush told me, "In elimination rounds, do what we say we can do or break the robot trying"... needless to say I did, and it worked
So, although it broke... it also went through more than its fair share of abuse
On another note, we did not have any 'sliding' issues, and if you tighten everything regularly you shouldn't either. For simplicity, teams that do not have access to welding can benefit greatly from extrusion
