When I was buying my first fretless bass (I think I was 11 or 12) it was between the RBX270F and the TRB5IIF (but in amber), and got the RBX (mostly because the TRB was too expensive at the time). Still have some slumbering GAS though, for that fretless TRB.
I have owned two TRBs:
I sold them both because they didn't fit my style and taste at the time but boy, are they awesome... I have the feeling the prices of TRBs are increasing after a long period of getting next to nothing for one: I sold the amber fretted 5II for about €500, but now I see people asking €800+ for one.