(I only got a chance to play with the new Mindstorms kit briefly in college to setup a small demo, they got about 25 educational kits as part of some grant. I just used the included software.)
I got to do FIRST Lego League in grade school with the RCX 1.5 and later the RCX 2.0
AFAIK the rules prohibited us from using NQC at the time. I believe we were limited to RoboLab [a separate product sold by LabView] and the stock Mindstorms software. (*Which I should point out is _nothing_ like the current software. It was geared towards very young users, very "flashy", and quite buggy. -- It did, however, include lots of media and examples for the robots in the instruction manual.)
That regulation was probably for the best, as my elementary self would've probably been frustrated by C-style syntax. I knew it existed only because our coach and assistant coach were both software engineers.
Actually, that's been my experience with the NXT-G language (the "current software") as well.
In order to test out a new program, I had to hook the brick up to my computer via USB, then copy the program over, then run it by pressing a series of buttons on the brick. Also there wasn't a good way to get debug logs in real-time (it's hard to read the screen when it's driving around the living room). Hopefully with Linux that process will get easier. The idea of SSHing into a Mindstorms brick, running a program, and watching the debugs logs on stdout is very exciting.
1. http://bricxcc.sourceforge.net/nbc/