When speaking about the block in the Manners; are you talking about the mini-chassis?
I have two Manners MCT-5's, one with the mini-chassis (7saum) & one set to run single chooter (6.5wsm).
I have a McMillan A-5 on my 6mm-284 and another (that should have been here by now) on order for the rebuild of my 338 RUM.
To be fair, the Manners are the newest to me & i'm still getting used to them. I prefer the A-5 as of right now but that may be due to being far more familiar with the A-5.
The one thing I can tell you w/o bias is the feel. When new the Manners came unpainted & my McMillan came in the gel coat finish. From that perspective the McMillan felt WAY better to me. Honestly the Manners felt like a 2x4 with a thumbhole in it. The bag rider surface was crooked as was the forend draft (flatspot in the forend where your sling swivels would attach). The McMillan was not. When I had Chad install the adjustable cheekpiece in my WSM, the butstock was filled with some sort of fiber crap that caused Chad to stuff some of his filler material epoxy stuff in there to have something to fit the fasteners too.. .to be fair the McMillan came from the factory with the adj hardware.
Now, yes those are minor things that can be fixed relatively easily, but for waiting 6mon or whatever & paying what I payed.... That's why I ordered another McMillan last time.
To recap, the Manners is a very strong stock & finished, it's very good looking I have no qualms about that. If I run out of ammo, I feel confident I could use my Manners stock to beat my intended quary to death
I tried pretty hard to NOT have my post sound like a Manners thrash-a-thon. I hope that's not what you took from it, I would own another Manners in a heartbeat if the circumstances were right.