The GB motos do look nice, but going by the pic I found of them fitted, they don't look like they will give you much rear-set!! (positioning wise, that really doesn't look any real advantage over stock!) ... its almost as if the bracket is up the wrong way too? .. the peg-to-bracket length looks very short too ...
So I agree, they look ace for the money build/looks wise, but they don't look up to much to the job in hand i.e. moving your foot back and up ...
To demonstrate what I mean, here are some giles rearsets ... and they are not even on the most rearward and/or the highest setting!! ...
Here you go, some jacked up properly
p.s. never used the GB's so only going on what I see and I really don't see any proper gain over the jack-up plates you have now!!