RE: HELP!!!! Which is better?
Just as a reference point, John and I were bashing with the same guy who had the E-Revo. He replaced the twin Titan 550s with the single 775 because the 550s were running so hot. With the gearing he had that day, he said it was slower than stock, but had a lot more torque. He was going to buy another pinion to get some of the speed back.
As it was, it was faster than a stock XL-5 Stampede. (which are pretty fast, IMO) It just didn't look as fast because it is so much bigger.
It is fast enough to be fun on rough offroad conditions, but not that impressive, speed-wise. It will probably run twice as long on a conservatively-geared 775 as it will on twin Kershaw HOs. You should also be able to run twin NiMH packs with no problems. So, as usual, it is a cost vs. benefit analysis that you'll have to do.