I'm also in the camp of normally only using regular alkalines. These remotes don't eat through batteries enough for it to be worth the hassle, IMO. (I use AA NiMh for cameras all the time though - much higher power needs there though.) Obviously you never place the remote in the base with alkalines in it though!
I actually received a little note from Lionel in my returned remote/base set back when we had to ship the original sets back to Lionel so they could modify them to take firmware updates. I would never dream of charging alkalines, but I guess some people would try it or forget and put the handheld in the base anyway. I can see from a general Customer Service stand point why they would feel it was important to place a note not to use non-rechargeable batteries in the box though.
-Dave
