It's a bargan and a lot of fun to boot. Not only do you get to run the track, you also take your turn working a bunker flagging and seeing some cool cars on track. You did fine at Hallett, you'll be fine at MSR. Just take the first few sessions to learn the track and have fun.
I believe they are running the 1.3 config, which I've yet to sample. Sadly, I can't make it. Have fun and be safe.