https://www.unitedhobbies.com/UNITED...hless_Boat_ESC
https://www.unitedhobbies.com/UNITED...idProduct=7188
http://cgi.ebay.ca/Turborix-AE-50A-B...QQcmdZViewItem

Cooling isn't too much of an issue providing you can either cut/drill aluminum.

Don't ask me why they are so expensive. All that's changed is probably a little programming and a couple transistors. You'll see more and more esc's with reverse in the future and prices will come down. There is a way of modifiying your current esc to add reverse. Essentially you would need a third channel to activate 4 relays, which would close and switch two of the brushless leads, then you would have reverse. Would require finding the right relays to take amps, buying a really small chip and adding software to a little chip that would activate the relays on/off.:

http://www.rc-cam.com/bitsw.htm

Would be pretty easy to do I think if ya follow directions and are a bit technically adept and have access to software burner or know someone who does. Still I think the flaw is flex drive, which is too bad, I've read people ravin that flex is the shi*, but I'm starting to disagree if the cable can't do reverse properly. I too wanted reverse for my new surface drive boat that I just made. I think the shaft needs to be converted to wire drive for this to be reasonable, cause juicing on flex in reverse one time might be all it takes to wreck cable and they aren't cheap and would be a pita to replace.

Ivan