Actually, when the RRR came out, it looked 75% like a MTX-3/R40/and a little bit G4. I've race all the Kyosho's since the V-one and have watched everything and everyone evolve, just like you have. They've gone more compact with the diffs, centralized rear diff pulley, longer arms, narrower bulkheads, rear upright hubs, similar steering block geometry, easy access... etc. Of course Kyosho made some of their own innovations. Everyones gonna take some ideas from others. It's all part of racing. If it works, run with it and make it better.
The weight of the reciever and wires above the top deck negate the low center of gravity of a laydown throttle servo. Plus you need more mounting hardware and screws, & more linkages w/screws, etc. A standup servo is still mostly under the deck but the entire mass is close to middle, light weight reciever to the outside, only a thin peice of plastic is needed to mount the reciever and cover it. Plus you're less likely to get fuel in the reciever. I run electric cars too, and 12-16g of wire above your top deck does make handling characteristics change. Although that change is more noticeable with EP cars on carpet, it's still an ounce torwards an advantageous setup to keep the wires low as possibe. And every ounce counts in racing. The idea is to keep all the major components centralized and balanced. That's why all the top EP cars are starting to look the same as well. Nitros will do the same ... at least till the next guy comes up with something new.
Don't mean to ramble, just trying to share thoughts and theories.