Shot the Mausingfield for 3 years in matches. It has never failed me. It is a smooth action, but on the heavy side in regards to bolt lift. Ran it in dusty matches without issues. And never had any issues with different brass brands, although i have heard of folks having issues with the claw and certain brass brands. But everyone I know who had an issue, it got fixed by Ted quickly.
Pros: Ability to run Savage prefits ; Smooth even in dusty conditions, Beefy Extractor,
Cons: Bolt Lift. Also the amount of tiny parts on that thing. ie. the bolt stop. Just hope that tiny hex screw in the rear never falls out on you.
The amount of Revision's out kinda makes you feel like a beta tester. Honestly don't know off the top what the latest revision is, and what all the differences are over the years. But buying the nucleus 1.0 and having a revision come out after waiting over a year for that thing was a little annoying.
For Impact Actions, I bought my first one late 2018. Wanted to have another action to shoot while gunsmith had the Mausingfield. I heard about how smooth it was and that Prefits were avail, so I went for it. After about 100 rounds or so on it, i was pretty much sold on it. Light bolt lift, and i knew it would only get smoother with more rounds and cycles. The Bolt Lift thing might not mean much to most folks but for me, that is less time i spend having to ensure my rifle is level between shots shooting off barricades/objects at matches. A couple barrels later, and Its really the only action I shoot now. I've gone thru multiple matches and only wiped down the bolt, and went to the next.
Pros: Smooth in dusty conditions. Light bolt lift. Prefits readily available from reputable gunsmiths; no downtime. Trigger Hanger; I have a spare trigger on a hanger ready to go in my match pack, just in case. Ability to just buy a bolt, and run 223 or Magnum.
Cons: maybe Cock on close might bother you , but that means nothing to me. Not much bolt Knob options, but that is minor.
I still love my Mausingfield, but at the end of the day i know which action Im picking up to bring to a match. Im still keeping my mausingfield for personal reasons and also being able to shoot cheap savage prefits with it using the Barloc. The Impact just hits more checkboxes for me and I feel super comfortable behind it now. Also, another pro to me is that IMpact actually supports the PRS/NRL matches. They put items on prize tables, and host matches.