I just searched for my reply only to find it appears to be missing. I recommended AA ".355 major" as you don't want to reload. If your not going to reload, I hope you have a lot of money because your going to go through a ton of $$$ on match ammo during live fire practice/matches. 9 major is now uspsa legal for open division only. The benefits to 9x19 is that brass is really cheap. There are approx. 25% of open divisions super squad now shoot 9 major. .38 super auto or it's variants 9x21 or 9x23 is expensive but can be reloaded upwards of 20x. That brass is thicker & tapered.(lapua, TJ, Supercomp are even thicker) Production is scored minor, so many reload mousefart loads. Limited and L-10 are scored major And .40 gives us more capacity is much grater than .45, though .45 is great for single stack and lim 10. To shave those precious 10s of thousanths of our times, capacity is everything. That's why use Bolen followers and flat wound springs with a Dawson SNL basepads with tubes, springs n followers are are tuned, polished. To a mirror like finish by Howard Smith available through shootersconnection.com they are also laser etched and rd. Indicator so you don't run the gun empty.
The big difference in STI and SV is that Sti has a bunch of "production" custom racers utilizing the 2011 hi cap frame as Sti makes them for SV as well as (strayer-Tripp international. Sandy strayer went solo and and builds 100% custom gns using their t-7 or 7075 barstock billet components. Sv will not sell frame kits, but STI sells them so you can build your own or have a total ccustom gun build.