The only downside may be the larger firing pin on the AXMC but even with the 6.5 creed there's ways around it. The right powder choice can keep the pressure curve optimal, and/or primers like Tula or CCI BR2's with a thicker cup will help prevent piercing with any of the powders. These aren't guaranteed however but myself and many others have ran creedmoor on LFP AI's without issue. Other options may not work out quite as well unless you want to bush your bolt so keep that in mind. Personally I don't want to bush my bolt so I just work around it. I have 243, 6.5 Creed, 308, 300WM, and 338LM barrels for my AXMC. I haven't shot the Creedmoor on this rifle yet but I ran a good bit through a 2012 AX with LFP and a 2014 AX SA with LFP without issue.
I like the weight of the AXMC, it really isn't noticeably heavier than a AX SA (like less than 1/2lbs?). The weight isn't too much for movement yet really helps the rifle stay planted when free recoiling. My only concern when getting the AXMC was the extended bolt throw when running SA rounds but I was assured that I wouldn't even notice it and I don't. It just works.
Was the rifle expensive with all the barrels and bolts, mag adaptor, mags etc? Yes, but still less than topping 4 rifles (the number of barrels/calibers I currently have for my AXMC) with $3K+ S&B's alone, not to mention the cost for each rifle.
The only thing better than an AXMC is an AXMC and a AX SA SFP. It's the perfect two rifle bolt gun system. You have a SA SFP version as your main comp gun for running whatever 6mm or 6.5mm flavor you want without having to worry about pierced primers or anything ever. Then you have an AXMC to run in magnum cals as well as have a 6mm or 6.5mm option or two as a backup rifle should your main rifle ever go down or experience an issue during a comp. Yes you're talking $25K for two rifle systems but it's worth every penny and you won't lust after another bolt gun. Call up Euro Optic, I'm sure they'll make the purchase a little easier on the wallet.