Good review, thanks for the information. I use mostly 21" mowers and also bag with the properties I do.
Right now I use an older Toro 4.5 hp Personal Pace RWD. I love that self propel system. I have tried several other mowers, and still think the personal pace is the best drive system out there IMHO. Just have to get a RWD version, never could figure out why people would want FWD.
I think when it finally wears out, I am going to replace it with this: