I just recently purchased an XS3 Pro and i love it. My buddy has an old XR3 and it was just to big for my hands. With the padded grip and adjustable trigger, i am able to adjust the radio to perfectly fit my hand. Even my old futaba magnum jr was to big, but this radio fits like a glove. Also, the RS310 receiver is quite a bit smaller than the RS300 that ships with the standard XR3.
I love the looks and feel of this radio and wouldn't trade it for anything.