Well, the big difference is that the TonePros bridges have a locking mechanism, Gotohs don't.
Whether the locking mechanism is worth three times as much... that's up to you. To some people it is. (To some people it's worth paying $4000 for a vintage bridge.)
I use the Gotoh lightweight aluminum tailpiece with the Tonepros locking posts. The tone of my SG '61 reissue did get noticeably brighter with the bridge swap and the tonepros locking studs are way convenient when changing strings. Sustain seems about the same to me as the stock bridge.. maybe a smidge more.. maybe my imagination!