Go for it! No, they're a direct bolt in other than the wiring. No changes to the chain drive system required.
I used a MAC 12t, as I could care less about speed, preferring max available grunt at speeds under 20mph instead - which is exactly what I got. The issue with that drive now is they are like hen's teeth, nearly impossible to find. They use many of the same components used to build the GMAC's, which offer a pretty special cutting edge feature - variable regen. That coupled with a very high quality motor has them in pretty high demand. You can look further into that pretty easily if you'd like. About 1100. with all the required electonics, laced into a 26" wheel ready to go.
This MAC 12t mated directly to the KT controller conversion I had already done to install the 1500 watt direct drive. I did have to match up the wiring, which might be a daunting task for many.
What might be a good plan, is a "kit" (from Amazon or Ebay) that would feature a KT controller and a REAL 750w Bafang geared hub. Something like that would be a very easy install, and likely have all the power you would want - on par with a fully modded RAD Rover.... -Al