There is lengthy, ongoing conversations on the GT thread... Some people are working on the conversion offered. There have been experiments with some metal gears. I have only had problems with the stock gearing when the mesh wasn't set tight. By tight I mean that there is no slop and the gears rotate freely. I usually turn the car on it's side (pipe side up) and loosen the engine mount screws under the chassis and let the whole assembly slide towards the spurs. Then, holding the engine in place, tighten the engine mount screws real tight. Now put the car upright and check for mesh. If there is the lease bit of slop... I will retighten until no slop.
I did go to a one piece engine mount. To me... it seemed that there was movement in the GT2 mount. When ever you would tap the wall (...err... or so I have heard
) there would be a minute movement of the engine allowing a little slop in the mesh and very soon a toothless second gear. I haven't had a failure since making these changes.
Also note that there is a 'B' version to the gear set that is proportedly made out of a different... supposidly stronger.. plastic.