Honestly, an 1/8th scale buggy with any standard RTR style big block engine is going to be pretty limited to around 45mph IMO.
Also, I have owned 3 buggies (just bought another), and Im 99% sure my jato would rape any of them from a standing start, roll, or any kind of race really. The buggies will jump a lot better and take much more abuse though. A buggy MIGHT get the jato off the line for about 10 feet because of the center differential, but after that, its over. Who races for 10 feet?
The way the Jato is setup with the 2 speed and the high revving small block in a light weight platform just lends itself to being really fast. Its probably the only r/c i have owned that has NEVER felt underpowered in any situation.
And for some reason a lot of people dont like traxxas engines, but my all 4 of them I have had (a 3.3, two 2.5's, and a Pro .15) have all run and tuned great. Really good engines IMO that make a lot of power for their size.