The best bit about Launch is that you can flat foot it at a standstill, the rev limit set at say 4k rpm. You actually make boost! WHereas if you just rev it to 4k rpm, you may just see the boost gauge flicker. Thats what makes the difference (IMHO)
I think you will find the only traction control that will work in a GTR is a light right foot , if 4 wheels are spinning then there is no measurement of true ground speed . Launch control is only useful for drag racing , where you can make more power by having WOT and building boost . my car makes close to 1 bar boost when I am using it , before I drop the clutch . it is very hard on the engine with an ignition cut rev limiter as it backfires alot .