I've had the Kidd lightweight, and the ultralight. The sporter is just another variation on them.
If I was building a Steel Challenge setup I'm not real sure I'd spend the money on a Kidd barrel, to be honest. Most people are used to shortening up the throat to attempt to kiss lead with it in an attempt to eek out smaller aggs. That's about the opposite of what I'd want in my steel gun, being as a FTF or FTE will cost you a stage most likely, and target size is on the 'large' size.
I imagine if you explained what you were looking for Tony would set you up right, but if were my dough I'd be looking for a light weight barrel to punch with a sporter reamer. Spend the rest of your money on a worked over and radiused bolt. I'd think weight/balance and reliability would take you a lot further than group size....