I owned many .38 Supercomp and I cannot sing the same tune as you. Even with Supercomp brass I still has issue with the 2011 mags and spring. Reliability is far from beign the exclusivity of the Supercomp ! The 9 Major is the same as the extra relaible 9 Luger with the exception of the long OAL of the bullet. My gun - polygonal rifling - hate plated bullet - undertandable at those velocities - by there is absolutely no issue with FMJ.
Choice of powder : You know like me that most IPSC shooter - when they have chosen their power - we stick with it unless it become unavailable.
You cannot beat a 9 mm for reliability - 9 major is used in more than one gun platform - many Glock are also converted and are more reliable than anything I have seen so far
Glocks are designed around the 9mm cartridge. 2011's and large frame Tanfos are not. 2011's can be made to work (Aftecs help a lot) and small frame Tanfos work fine. You say yours works great but you don't mention how many rounds you shoot through it, if you shoot only in Canada (10 rounds), or if it is a large or small frame. You don't say if you ever get any jams in it either, and many folks who tell me their guns run fine don't mention that they might get a feed jam every 1000 rounds or so because they think that is acceptable. I don't view that as acceptable in a competition gun.
Buying a racing gun is a case of managing variables, and the more varaibles you accept, the more likely you are to run into issues. this problem increases with the number of rounds you shoot per year. If you only shoot a couple of thousand per year your gun may indeed run fine so far, but if you shoot 40,000 rounds, well that is a different matter.
If you have narrowed your window of functional reliability by introducing the dimensional variations you get in typical 9mm brass manufacturers, and by shooting a caliber that the platform wasn't initially designed around it means that you will encounter these issues sooner than later, mathematically speaking. That's just reality. There are things that can be done to make the 2011 work...most of the time. But without a better magazine design for the large frame Tanfo, i can't recommend it for 9mm major.
What I am trying to do here is not steer anyone in any particular direction.
Rather; I am trying to give them the benefit of years of hard experience, research and knowledge of these particular designs so that they can make an informed choice. I cannot in all good conscience tell someone something is great and it works wonderfully when the only data sample I have is my own personal stuff, and without providing a credible base-line from which to consider the data.
By all means, if 9mm brass is cheap and available and you have someone who can set up a 9 major gun for you, fill your boots. I know lots of guys out there will tell you their guns work fine, and they may indeed. But if you are buying a 9mm major new yours probably won't (statistically speaking) until you get someone knowledgeable to work with it. So be prepared to accept that you may have to do a lot of constant buggering around to keep it in the game. For my money, one major match blown because of a death jam on a 160 point long course totally negates the supposed savings in going 9mm. It's just not worth the frustration.
and yes, I know that all race guns require tuning and babying to some degree. That is not what I am referring to. Once a super is set up and tuned it should run until wear and tear issues intercede, and if you are doing things correctly you should catch that stuff before it comes up. A gun that is designed for a longer round is never going to be an ideal platform for a shorter round, and that's not going to change. It's about risk/vs gain for me.
FWIW: My last batch of Supercomp cost $160.00/thousand. I lost about 2000 cases last year at matches, so a difference of $320.00/year.
Try Aim 124 grain plated bullets in your Tanfo. They are hard cast rather than swaged from soft wire, and plated extra thick. They should group around 3" at 50 meters out of your polygonal barrel if you are capable of it.
So for those considering their options, good luck with the choice and may you have many hassle free rounds down range.
R