I have all of them now except for the #21 and I should be getting that soon, I haven't had to use the swirl remover or the dual action cleaner polish yet, but will get a chance to try that out on an older vehicle within the next week or so.
I've done my MS3 with the #7 then #26 a couple times now and I really like the results. I will probably play around with multiple coats and throw the #21 into the mix next time and see how things go, overall for the price and easy availability I really like the Mirror line.