I write and record music in my own studio for TV since 1996 and I use the Axe FX mainly for live situations because I can't carry 4 amps with a bunch of cabinets to a gig due to back problems. In the studio I use many amps( ENGL Powerball,Frieman BE/HBE, Splawn Nitro, Metro moded by Bray amps, custom made Aracom PLX100,Groove Tube GT75 Soul o, Voc AC 30 and Vox Night Train and more to come!) through a custom made dummy loads power by either a Mesa Boogie 2 90 or the power amp section of any of my amps. I have 3 Marshall cabs, a custom 2 x 12 with many different speakers( Celestions V30's Green backs and Scumback, BM75,M75,H75,S75PVC and Scumnico) all mic'd with Shure 57's and Roger 121's ready to go.
Like Dutch said, I haven't been able to gel without tubes and I'm getting incredible tones with my amps. But I have used on occasion my Axe Fx 2 with my 2 90 or a Matrix GT1000fx with great results when I need a sound that I can't get with my amps. With every Fw upgrade the Axe Fx 2 is sounding better.
I do use the Axe Fx 2 a lot as a bass amp using 2 amps with one dirty amp and one for clean with IR's with great results. A couple of days ago I tried the new the new Pack 3,UltraRes cabs mixing them with Cab Lab 2 and I was really pleased with the what I heard. Fw 14 has improoved the sound of the Axe Fx 2 quiet a bit, but I still use my amps! I guess I'm just an ld dude!