Going back to the original question between the GT2 and the XXX-NT, I am going to go with the RTR XXX-NT simply because it comes with a JR Digital Radio. The radio that comes with the GT2 RTR is a pile of SH*T!! IMO. The GT2 is a great truck, but the radio is worthless. If you are looking to buy a kit truck, the GT2 and the AD2 losi are very good choices and are capable of winning any race. However if you are stuck on getting a RTR kit, then go with the Losi XXX-NT. It has tons of power, very easy to start, and the radio is worth the extra cost.
Good luck on your new truck (whichever you decide)