Jason:
I dont have a rear locker so I cant speak for using BTM along with the locker.
As far as BTM goes. Your thoughts sre correct. You Can feel the truck begin to crawl. I dont think though that I have ever looked at my engine RPM while using BTM. I am no expert on this I just do it by feel. I am just very careful never to let my wheels spin.
You should try using BTM without your locker on and see how it feels if you have not already.
The one thing I have to think is BTM has to be hard on the drive train. I think this is the best argument for lockers. I did break the output shaft on my front diff once while using BTM. Im sure the shaft had been stressed before this but I believe BTM is what broke it. If you go to the following link you can see a video of the breakage, It is at the end of the video.
http://www.wisconsinhummerowners.com/Secret.mov
It is about 115 Megs.
It also has a scene that shows a Humvee with ARB lockers in the front and back crawl up a pretty steep rock face.
Mark Weber
Webman
www.wisconsinhummerowners.com