Rob, I know I thought lipo was the way to go when you first raised the question with the Slash, but I think the lack of a LVC in the ESC means the only responsible way to set the class up for racing is with Nimh. I'll practice with lipos myself because I am very comfortable that I can manage the voltage level myself, but to put an inexperienced person into lipo without the safety of the cutoff is just not responsible. That factor trumps any other concerns...and this is coming from a guy who hates the thought of having to run nimh again!
Heard you looked pretty sporty in 4wd last Saturday...