Can't imagine the newer units will have lower (less) power than your 4200, and don't think (or didn't at the time) the 'power' discussions herein were comparing the older series with the new series. Some just expected more power than they were getting (which may be what we all run into at one time or another). As far as selling or trading, I would talk this over with my dealer. You may want to do that too, and decide if you want to buy outright (in my state you pay the full boat on the tax vs. paying tax on the difference) and sell yourself.
I don't like selling things, as people show up that are just there to hassle about price and leave you hanging. I sold a skidsteer once only to have it come back the next day (his job was done I guess) and complaining about an oil leak. I didn't see any oil on the trailer so figured there was some other thing wrong. I started it up, drove it off the trailer, listening for something wrong. Soon as I went about 10 feet from the trailer, I turned around and saw the trail of dust as he exited the driveway in a big hurry. He didn't even ask for his check back (I found out the next day Monday that he had already canceled payment on the check that he wrote to me on Saturday morning). Turned out the skidsteer ran fine, was a bit dirty from the work he did, and the 'oil leak' was a once-a-day drip from a seal. There is a lesson there somewhere. /forums/images/graemlins/crazy.gif I expect I will trade up, rather than buy new and sell the old. Just my thoughts.