I had a V12 9mm for a short time and these were my impressions:
-too many barrel holes for 9mm
-too few ports in the comp (two small top ports, no side ports)
Because of these issues the setup needs 9-10 grains of powder to shoot flat. It shot like a dream with 10gr of SP2 and a 100gr bullet, but the minimum bullet weight for Major in USPSA is 112 and 120 for IPSC, besides that load only made 152PF!
With a 124 it took 8.4gr of HS6 to barely make Major with a short OAL, that's a high pressure load so I don't think the barrel lugs of any pistol would survive that very long.
I think the V12 could make a good shooter in 38 (although you'd be burning a TON of powder shooting Major), but you need to stick to minor if you want the 9 version to last.