Don't forget tamiya's line of entry level TC like the TT01, TA05. Tamiya tried several different layouts, but it seems that the 415 one is race proven. The 416 is pretty much the same deal with updated parts. The scary part about tamiya is, you can buy a TA05, and spend so much money on hop-ups. I spent more money on that car than I did on my TA05MS. Well, I guess that's why they are so successful.
Aside from that, I think TC is at it's peak in terms of current design. I guess it is like F1, where the general design has not changed for a long time, just refinements. Thus the 416 didn't go thru a drastic change. If it works, don't fix it.