I did about 5 straight hours of sanding, renovating lawn furniture.  The 3M-Cub2 disk finally gave out after 5 hours, the backing turning to lint.  I put a junk disk (came with the sander) on it:  it lasted about 15 minutes, then started disintegrating.  The 3M-C2 face was still abrasive after failure; the cheapo was almost as smooth as the proverbial north-bound baby's south end.  Simplifies my purchasing habits!

Thanks for the information!

Thanks Pete.  I will have to look for it and give it a try.

UPDATE:  3M has a newer version, "XTRACT", which has a mesh backing and a pattern of grit rather than continuous grit coverage (the pattern appears roughly 35~40% grit coverage).  The "old" Cubitron (with 100% face purple grit, and cotton backing) lasted for about 1.5 hours of sanding per disk (an imprecise measure, yes), at which point the disk flew off the ROS since the (cotton) backing had disintegrated.  I've kept all those "backing failure" disk because the grit works really well with a sanding block.  The grit "bite" is indistinguishable from a new disk.

     Working on the same teak chair set, I find the new XTRACT still does a great job,  but now the grit wears down before the backing gives up.  I think the disk still lasts about 1.5 hours, but at that time the grit is noticeably worn, significantly less "bite" than new.  

     On both versions, a sanding paper cleaner (like a big dick of dried rubber cement)(a frankenstein dick) seemed to help; the new XTRACT benefitted more from cleaning.  

     I surmise 3M figured out if they made the stuff TOO GOOD, they would truncate future sales?  I still think the XTRACT works better than any other paper I've tried, and at 52 cents a sheet, divide by 1.5 hours, multiply by arthritis, subtract naps....hell, I lost track, but I bought a pack of 50 so I'm a fan!!!

I had picked up some of the Extract disks some weeks back and tried them. I was more focused on dust collection and found (with my setup) they didn't seem to do as well as the standard 8 hole disks. I haven't used them enough to evaluate the life, but there's little doubt in my mind that they will outlast the aluminum oxide disks by a long shot.