i NLS as well when at the track and sometimes on the road when i feel like it, tho i don't do it often. it is a hard habit to break when you're use to lifting for every shift, but once you get it, you'll love it! i NLS on 2-4th gears with a stock trans and on a stock clutch before i switched to an exedy twin disk (still a stock trans) and have had 0 issues.

good luck with the rebuild, and sorry to hear about that i would re-look at what you're 2 step is set at....seems too low IMO

 

My 2step is at 6k rpm but I havent launched yet due to the weather in the negatives... Dont think the outcome will be good :\