the gtx 260m is better but I probably would't make the swap 6650m. You have a newer quad core cpu and it is lighter laptop.
that model (the g72 bestbuy model) laptop in particular is know for heat issues. plus it is clunkier than your acer. also with that laptop due to it being a best buy model. You are limited to dual core cpu upgrades. You cannot put a quad core in it.
I currently own the g51 rx05 model of that lappy, It runs hot and that is after extensive cooling modification.
do a test run trade, if you like the performance of the g72 then keep it.
EDIT. also the battery life of the 260 model is pretty horrible (like 1 hour on power saver), that probably doesnt matter too much but considering it is a gaming lappy but its noteworthy.