I was one of the few running a shot on my SS back in the day. Do a search under my name "FoShizzleLude00" in this nitrous forum for some of my threads. I ran a 50 shot dry and it brought me from a 16.3 to a 14.5 sec in the 1/4.
IMHO it was a worthwhile mod while I had it. I only stopped using it because it took a while to heat the bottle up to pressure and feel the full effect (not optimal for instant street runs). As mentioned above, the best effect was felt in 1st and 2nd gear and it really made the SS move. My transmission was fine. Tho I stopped spraying in 2004 and my SS went out on its own this year at 94K miles (thankfully, covered by warranty extension). I don't think the nitrous usage had much to do with the SS failure since it has been 4 years.
If anyone is interested in a great deal, please check the PO Personal Classifieds as I just put all my nitrous goodies up for sale. Including NOS Dry Kit, Purge, Remote Bottle Opener, Digital Nitrous Gauge, and Bottle Warmer. Make an offer on any of those!!
FS: Used NOS Dry Kit (#05123) and Tons of Nitrous Accessories!