I would strongly suggest to anyone out there that runs something a little heavier like a MT or a truggy to ditch the 1515 and go with the 1518. I just did it to my Revo thanks to the Castle Sale.

Anyway I left the gearing the same as with the 1515 2200kv motor just to see what would happen but I knew I had to gear up. 18/54 is what I ran with the 1515 but the 1518 felt very slow and uninspiring with it. To gear up to the same top speed that I had with my 1515 I moved over to mod1 gearing for the 1518. 16/40 would put me in the same ball park as the 18/54 and it made a huge difference. All the speed and power was back but the motor seemed to run a little cooler too. Not much. 4-5deg at most. Still plenty cool and I went up to 17/40 gearing. It just got more powerful but there wasn't any difference in motor temp.

The short of it is IMO it is a win-win situation going to a 1518. Everything seemed to run a little cooler so I am guessing that it should be a bit more efficient. After all heat is lost power. Less heat = less power lost.
Hard to say about run times as I mangled one of my rear drive shafts on the second run and I wasn't really paying that much attention on the first run (I was concentrating more on temps). I am sure if the same gearing was to be used the 1518 would come out tops in that comp.

Now a question time (feel free to help out here NUZ69). What can I expect if I was to stick a 1717 in the same truck and gear it for same top speed. More torque is the easy one but what about efficiency? I am going to do it soon but would like to know what I could possibly expect.