I've run Redline in my 32R since I bought it, both engine and g/box approx 12,000K, my R makes 430 RWHP on the original build. I dont do anywhere near as much motorsport as Troy-a few drag meets here and there and the ususal spirtied driving I suppose, but when I changed over I immediately noticed the g/box felt firmer in the shifts and to date my oil pressure is still the same.
Not sure about Redline not recommending g/box oil for synchros but I wrote to Redline and recieved written recommendations, though i'm going to check out the site again though just to be sure.
As for Motorsport, Redline has a long tradition of providing lubricants to many teams in American motorsports. As an example, next time the NHRA fuellers or floppers are on check out who sponsors them. Sure Team Force is Castrol but look at the rest. Having said that, what's on the wing or container isnt always what's in the container - it may for example say Fuchs but it might be Redline
In the end its whatever your comfortable with and what your pocket can afford.