I don't have a Muscle brake for actual comparison though I do have a PK on a 375 Allen Magnum.
The PK is super effective compared to results of the Holland QD on my 338 RUM.
I think highly of Jim See's Muscle brake and will have one on my next build.
I think the decision will come down to cosmetics as I don't think the two brakes are all that similar. Jim as an innovation in his that allow it to be a bit smaller, I think.
I like the big slab of the PK for macho on the 375 AM.
But it does add a bit of weight.
Recoil wise I doubt there is much if any noticeable difference.