Just my opinion, but I think it has a lot to do with the climate you are in.
My original experience with this product was in California. I was using the original formula, and it worked absolutely fantastic! I had absolutely no complaints what so ever. Brought some home to Texas, and I couldn't get it to work for nothing! Gummed up, and totally useless. It didn't matter what pad or speed I used, nothing worked. Many talks with Kevin and Jason, and I'm still not sure if we really ever nailed down what happened, but IMO it was the different climates.
The new M105 is an excellent product for me here in Texas. Usually I can get some pretty flawless results with it. I still have a quart of the old formula, and brought it out the other day, just to see if anything changed. Gummed up almost immediately, and was a bear to use.