Nothing wrong, per se, with upgrading a bike you already like. The problem is, you are talking about upgrading from entry level 7 speed Tourney to enthusiast or mountain bike grade 10 speed, which means switching out shifters, derailleurs, and back wheel. And you still have entry level frame, cranks, front wheel, and V brakes. The question is, does this make sense in a bike that retails for $360? Don't get me wrong. I have spent hundreds in upgrading and overhauling bikes, but it was usually a bike that had sentimental value rather than something I just bought. Might it not make sense to just sell your Escape 3 and look for a deal on a new, or slightly used model a little higher up the food chain, if upgrading is your inclination?