Ding Ding, Round Two!!!!
(Sorry, couldn't resist!)
I dont want to get involved in the debate as I've only used one system and couldnt make a qualified comment about anyone elses brand, but I can tell you this...
I, like most other CND techs, use a koala to remove shine from the natural nail during prep. The koala is a 240 grit. I find this job best when the koala is old and "dull". I recently had to change to a new one as the old one was looking bad and was starting to look bad to clients that I use tatty files, and I hate the new one. I'm cringing when I use it to remove shine and I'm doing it very gingerly because in my opinion, even with a brand new 240 grit, you have to be extremely careful, I dont want to scratch the nail, just remove the shine.
That said, I would hate to think what a 100 grit would do!
Again, I'm not involving myself in any brand debate, if other brands advise it, I couldnt possibly comment as I know nothing about those brands, but my experiences of removing shine with a 240 tell me that a 100 grit would be really harsh!