This is a bit apples and oranges to the OP's question, but here goes... I have an MPA BA in 338LM. Getting it on target at a mile with factory ammo was straightforward in challenging conditions. While breaking it in, it shot right at 0.5MOA 5 shot group at 1K yards. After bedding the action and using handloads, it shot 0.3MOA. I think of the MPA as a sort of "custom light" rifle.
I also have an AX/MC in 338 LM. It was also straightforward to get on target at a mile with factory ammo. I have not gotten quite the advantage from handloads comparatively with the AI but it grouped a little better compared to the un-bedded MPA.
Here's the thing - I feel like I'm going to shoot better when I'm behind the AI. It's heavier than the MPA and thus I feel less recoil, but once I got the AI tweaked to my liking, I saw way more impacts because I'm staying on target nearly every shot. I do like the trigger hand position better on the MPA but I can shoot the AI just fine within my own limits.
It was out of character for me to spend so much on the AI but I'm happier than a pig in shit that I did.