I don't know much about the T-raptor but I ride a T-rex wich I've had for nearly 2 years and It's still going strong, so I'd say Onza seem pretty good. I hear the garentees are good aswell. As for tips, just IMO but I would get some shin/knee pads (and a helmet of course) and then try to ride onto some low walls, as you progress increase the height. Also don't be put off if things seem difficult at first, just keep going. Good luck.