Especially if that's what your wife likes. Can't go wrong there! 

I have two, the first one is a 20 year 721 old that I got new and haven't done much to it other than maintanence, a couple belts and bearings. It has hardly ever mowed a lawn, just weeds and some cemetery work.

I got a new 620 last year just for lawn work. I think I still like the old 721 better for some reason that I just can't quite put my finger on. I know I like the 3 cylinder liquid cooled Kabota better than the Kohler.