Yes it would have killed on-line ammo sales completely in CA - which if nothing else would have effectively killed the 10mm in CA.

Lots and lots of hard lobbying by phone and e-mail actually made a difference for once 

I have a 6" non-ported in 10mm and a 6" non-ported in .40S&W for my G20 SF.  I have had the both for over a year and have put ~ 1000 rounds through each, ranging from low energy PMC up to nuclear Underwood.  No problems with either.  Both are well made, accurate and give full case support (i.e. no evidence of case bulging).

I'm not sure if its my imagination but the 6" 10mm barrel seem quieter (from the shooters perspective) than the factory 4.6"