Since Menzerna Heavy Cut Compound 400, i have not used Meg's 105 too often. I'm with you, Steve, in that i absolutely love Menz 400. The key is the difference in the abrasive technology between the two. Menz can be worked almost forever and i take it to that "flash" indication. It finishes down so well. Meg's 105, as a non dimishing abrasive has a shorter work time and very very frequent pad changeouts. Plus a spray bottle of distilled water does wonders to extend the work time a bit. When i'm faced with a severely trashed hard paint i still grab M105! I find it corrects faster and that helps when the clock is ticking.