I read on another forum that collets should be replaced about every 400-600 hours to minimize run-out. Is this the case f or the X-carve, and does Inventables have a recommendation for an hour meter (maybe dc spindle voltage operated?)
Was that from a metal working forum with industrial size CNC machining centers. There could be a issue with fretting of the collet on a machine that is pushing the limit of feeds and speeds for there collets.
I do not think you are going to push those limits on an X-Carve. I run ER 16,20 and 25 collets on my CNC mill and see no problems with fretting.
I think it was from the Onsrud site that referred to cutting acrylic plastics. It may have been referencing industrial machines.