So for CMP the majority of what Ive seen is the .45 cal being shot out of a 1911 platform.   With the advances in 9mm will it surpass the .45 as the popular round for the 1911?   What is it that with the .45 ballistics that still have it as the best round for this distance and competition?  Does it shoot flatter?  I can get all of the benefits of the 1911 but have less recoil for the times phases with the 9mm.  Please school me!

I only shot bullseye once. The bigger hole of the .45 is probably its biggest advantage over the 9mm (assuming they score based on the actual hole). I’d guess you can download the ammo for similar recoil levels (not sure if there is a minimum power requirement).

I used to shoot PPC, various distances out to 50 yards.  I used several platforms in 9 and 45, HK, Sig, glock, Ruger, I was always better with a 1911.  Farvorite was a first year of production SA Operator TRP long rail, will never part with it

1911 is used because there are decades of gunsmithing experience on how to make a 1911 accurate.

.45 (in general) is a fairly accurate cartridge, partially due the the short case, and also because it is natively subsonic.

The 1911 is still very popular due to the decades of tradition. Plus the relaxation of the required 230 g. round nose bullet has helped the .45 caliber remain popular. Plus many shooters are already set up to reload for the .45 ACP so no more equipment is needed. You may get a hair more accuracy out of a 9MM with a custom barrel and tuned ammunition. Qnce you get the ammo to function the slide in a 9MM 1911 there is little difference in recoil. As I understand it, the 115g. Bullet at around 1100 FPS is where the accuracy of the 9MM best shines. The biggest advantage of the 9MM may be ammo costs if you have to buy new ammo.
A good shooter will have high scores regardless of which caliber he shoots. The old saying " It is not the arrow, it is the Indian"

Thats why I shoot 40 cal in IDPA. More break the line chance and minor power factor 40 is like a 22lr in my G35.

tag

45ACP is a very good round for accuracy, 9mm is far more finicky to get it to shoot well .

A decent factory 1911 with good adj rear sight and reasonable trigger is generally going to be good enough to get EIC points these days. I have shot a few 260-70's with my factory SA loaded with softball.
 I have a 9mm SA RO but it doesn't shoot very well pretty much a 9 ring gun with every factory 9mm tried. Went distinguished with custom hardball gun yrs ago.

In sports that favor scoring, larger bullets (45 > 9mm( have an advantage, as long as you can reasonably control for recoil. In sports that favor speed, other factors can be more important. Telling is that in Bullseye of old, where you shot .45, centerfire (i.e. 9mm, 38 Special), .22LR, most folks skipped centerfire and shot their .45 again.

X ring is about 10% bigger for a 45 vs a 38/9.

If you sink money into souping up a 45 that gets you the best results and most use cases; cmp leg matches as well as nra centerfire and 45 matches (last 2/3 of a 2700).

If you built up a 9mm you could shoot leg matches and 1/3 of a 2700.  

As for 9mm non 1911s consider;
-The 5.25 xdm is probably the best deal and very likely cmp competition ready.

-Sig p210 target needs about $10 of springs to raise the trigger pull to the required weight, that done those are as good as anything.

In bullseye it may be the indian, but it takes a darn good arrow too; five shot groups of 3" or less at 50 yards.

9mm is supposedly more inherently accurate than the .45.  However, it is much more difficult to develop a 9mm load accurate enough for bullseye shooting.  Some bulleye shooters are using the 9mm for the centerfire matches because the centerfire gun only needs a 2 1/2# trigger vs. 3 1/2# for .45.  There really isn't much difference in recoil because you need to push the 9mm loads to get the accuracy. I did tease a high master telling him his close shots would have been in with a .45.  Don't confuse this with leg matches, the trigger needs to be 4# for leg matches regardless of caliber.  My opinion for leg matches is the 9mm and 45 are about even.  You can get a little more accuracy out of the 9mm, but are loosing out on your close shots.  I made distinguished with 45 hardball factory loads back in the day.