Shockproof is great in the transfer & rear diff but I didn't want to run it because of this, quoted from TRE's page:

There are concerns about using REDLINE SHOCKPROOF type gear oils inside manual transmissions. While this is truly an excellent product, it has been found that the heavy paraffin-like particles are quickly centrifuged out of the oil and build up inside the center diff housing and around the synchronizers and inside of the gearshafts. After several oil changes this build up may block oiling passages inside the gearshafts that lubricate the needle bearings and can reduce the overall effectiveness of the synchronizers, leading to poor shift quality. Also this oil is has too high of a viscosity for winter use. Therefore we do not suggest using SHOCKPROOF in the transmission unless the transmission is to be serviced often or a dog box.

Are you running straight SP or is it mixed? Maybe this isn't so much of an issue when your mixing the SP with reg fluid? I know a bunch of higher hp guys on the link board had said they ran some version of a mix with the SP but I don't know if or how often they had the tranny out for service.