I use
Meguiars and find their products very nice. Their Super Micro Abrasives still break down (a diamond breaks down) just at a much slower rate then a traditional polish.
I use
M105 (infact I was one of this first on this board, IIRC) quite often which also features the same abrasive, but I have limited expericene with
M86 (So1o) polish. When we talk about automotive refinishing, their is a huge spectrum of people doing different quality work. I think for "autopian" style work (which I view as doing the best possible job) you can generally get better finishes with a diminshing abrasive polish.
The last time I spoke to Mike Phillips on the phone he told be (I believe) that
Meguiars actually used System One as a bench mark when they developed the So1o line.
I think M105 (which can be very finicky) is one of the nicest finishing compounds on the market, so my opinion of this technology that it seems to have a huge ability remove defects but doesn't quite finish as nice a dedicated finishing polish.