thanks for the endorsement pixel. for a while there, no one was using 's' at all, and I thought it was just too weird to be learnable, and I just knew how to do it, because I had made it.
krush, I have almost no plugins I can confidently claim this for, except 's'. it is very stable, I use it in almost every project I make for the the advanced picking features.
It is easy to make it crash, but it's almost always an error like pixel said, where you misspell the name of one of your arrays, or otherwise mess up an 's' command. I warn you though, it's got a learning curve. It changes what's possible to do in construct, the same abilities you have with the c++ sdk as far as object manipulation, so in order to make that work within the confines of a program that wasn't made to work that way, it has to be a little weird. But I've used it in large caps where it used 's' stuff 1000's of times per tick, with zero stability issues.
one of the few things I still have the source code to, also.
one last thing, there is a little known feature that can help you along your way is the debugging features. in start of layout set the debugging output file, and for many crashes it will popup a text file telling you what you did wrong.