i ran the 260AI for a long time (about 30 matches over past 3 years). i'll go back to it if i can't get my 6cm rebarreled soon.
i've run it from 3047fps to 2960fps. (i'd target 3000fps on a new bbl to save primer pockets)
i don't mind the fire forming at all, and since i wouldn't run new brass in an important match anyway, i'm essentially fire forming every caliber. so what difference does it make? besides, fireforming brass is what F-class matches are for.
further, i got over 10x firings on the cases i managed to keep and never had to trim a single one. i would probably scrap 3-5% before the first shot because i neck up from 243win and then fireform (so necks would split before i even shot them) but the ones that survived pretty much would last until i lost them at a match. (or ran them so hot that pockets wouldn't hold a primer)
early on, i had feeding problems but that was mostly the action. once i got it sorted out, it's been reliable enough for matches.
barrel life for me was 1500 @ 3047fps, 2600 @ 2970fps, 2400 @ 2970fps, 2000 @ 3000 fps. i put more rounds on several of the barrels, but that's about where they started flaking out on me
edit: btw, you can fire standard 260rem in a 260AI. how do you think you fire form it? and it shoots well enough to win f-class matches while fireforming.