I don't have the collets, but I can comment on the stability of the 2V valve gear. I replaced every shim at 12K. I could have buttoned it up with out changing anything. All valves were within spec. Since I had just received my EMS shim kit (very highly recommended), I had the stuff I needed to get things to a tighter tolerance. I completed my 18K valve check early this month, and again, I could have left everything as is, but I ended up changing out two closers and one opener. I set my valves to .004" on all openers, and less than .002" (most are less than .001") on all closers. I ride the bike easy during the week for my daily commute, but it does get a lot of time in the 6 to 8K range on my weekend "sport rides".

Opinion time.... I would say if you do your own maintenance, skip the collets, and buy a shim kit from EMS. If you're paying for service, probably worth going to the collets and doubling your maintenance interval. The valves are pretty stable once things settle in.