I have a Tiberius T9.1 - the hand grip is massive and the overall pistol is larger than a Spyder MR1. That being said, it's a cracking piece of kit. The old Splatmasters are a hoot to use, but you have to recock after every shot.
Ask your friends if you can play a game/s with their TipX's (just the TipX only) and see how you get on with it. They have a good reputation for a reason