what tonal change do you guys hear with the lighter tailpiece?
I've got one on my Swamp Ash SG.
I'm pretty cynical about these things, but even I could detect a small amount of extra top end 'zing', and definitely more sustain.
I've got an aluminium wraparound on my LP Jr. It definitely made a very noticeable difference when I fitted it, it seems to emphasise both bass and treble somewhat (but
not in a harsh, piercing way) and the guitar is louder acoustically.
Not sure about sustain on mine, it may have actually
decreased a little, but that may be because the note rings louder initially so it seems to tail off quicker.
For comparison, I have an identical Jr which still has the original zinc(?) bridge. It sounds less lively but on the other hand seems a bit more focused and "solid" when playing chords, there's more chunk in the midrange. I do have an aluminium bridge for that one too, it'll be interesting to see if it ends up sounding like the first one or if they're just different anyway.
I suspect the aluminium tailpiece isn't something that automatically "improves" a guitar, it's more like a way of fine tuning the tone which may suit some guitars but not others. I've got 2 or 3 of the Gotoh tailpieces which I'm going to try on all my T-O-M guitars (eventually!).