Manners get real pricey when you try to upgrade them to compete with the standard features that come on an MPA. I just bought a PRS1TK. $1200 baseline. Now have to pay to open the barrel channel for a mundane normal contour like heavy palma, bed in a Henderson Mlok rail, $200 for an Area 419 rail. The thumb rest indent is in a wierd spot. I don't know who the hand model was but it doesn't feel natural.
I used XLR for a couple of years. I liked them but their failure to innovate quickly had me migrate to MPA. The need to have tools on hand to adjust every thing was a minor annoyance. Really, when they debut'd the Envy with all the teasers "Something big awaits!" And then , boom! ...an element with a few basic features built in...a half pic and half Arca rail. At that point I left. The current Envy looks a lot better but I'm diehard invested in MPA for comp rifles.
I haven't tried an ACC. It really just looks like they ripped off MPA and tried to improve on all the innovative features MPA has standardized. Perhaps they did improve on them, IDK. I know a lot of guys that switched from MPA to MDT bc they were tired of MPAs customer service, which I totally understand. I would say MPA is up there with some of the most frustrating CS I've had to deal with. They couldn't make a projected deadline +/- 20% if they tried. And what's worse they don't bother to update you. You have to contact them and when you do they initiate the Australian Peel, smoke grenades, and flash bangs while shrimping away.
Here are some things I like about them. Manners: looks, texture and feel when hunting. MPA: the family of upgrades and accessories. Phil's constant innovation. AI: their folder lock up is probably best in the biz. XLR: customer service is awesome