I got a trbx504 not long ago and love it. super thin neck. weighs under 8 lbs. I got it as a slap bass. While I have instruments that cost 6x's the cost, I gotta tell you, its a quality instrument that I really enjoy playing. Like $500 new and has a super narrow neck with a small radius.She has already tried an RBX170 and a 260 and they weren't it. I already knew the BB300 would be way too heavy, and plus I'm sitting on that one haha. I don't know a whole lot about the TRBX series, though!