The gears are not really the problem with the trans IMO. The gears are plenty strong enough for more power....
The weak spots are really in that the input shaft has quite a bit of flex to it, due to the fact it is hollow to allow the clutch push rod to pass through, and not very thick. When you consider the flex of the input shaft and thin cross section it will twist and break given enough power/torque. Then add to that there is not a real way to control the thrust side load in the DSSC trans other than the small annular bearing...
The input shaft bearing takes the pulling load of the engine in one direction, the weight of the clutch and carrier hanging on it, the shaft being pushed in another direction as the helical cut gears side load, plus the added stress of flexing making it a complex problem. I have also seen the splines sheer off the input shaft, or twist given the shaft does not break first.
Taking metal away from a 90 degree edge can make a part stronger by giving it a larger radius instead of a sharp stress point at the 90. Same idea as what I have done to the crank in my 598ci big block chevy and also very common in the race automatic transmissions I build. It has to be taken away at a proper cut and angle.
The problem is the input shaft bearings are not going to handle the side loading of big HP and there is not enough "meat" on the input shaft for any large HP gains in that trans...It just will not take it long if ridden hard. IMO cutting of the dogs (that have plenty of room as is) only allow the gear to slam into position harder shocking the shaft as well as the bearings, much like a neutral drop we all did as a teenager just making the problem worse.
Best things to do for the DSSC transmission is good quality bearings, making sure the radius cut , and heat treating have been done to the input shaft.
