Yes, I only used the word rig to irk you!
Anyway, currently using Time XC8 and S-Works XC shoes, and they're just fine and dandy. However, am pondering having a set of road clipless for the summer months. Far less likely to be stuck out in the muddy gloop in the summer, so,the need for walkable(ish) shoes is lessened greatly. Summer rides tend to be about. A 60/40 split between the back roads and the tracks and trails.
Shimano R8000 Ultegra, or Look Keo 2 Max.
Which and why?
I do a similar road/off road mix to you and I've used Shimano SPD-SL pedals off road for ages on my cross bike - I don't like the feeling of MTB pedals on the road. I don't get off and walk, so it's not a problem. They take a surprising amount of battering (dropoffs, mtb trails, Dirty Reiver 200km etc). Shimano all the way for me. Worth saying I don't do cross racing, where road pedals would be idiotic.
If you're going to put a road pedal on there then I'd definitely go Shimano over Look. The bearings and the cleats both last longer.
<span style="color: #444444; font-size: 12px; background-color: #eeeeee;">the need for walkable(ish) shoes is lessened greatly</span>
Lessened or eliminated completely?
If you're going to walk much further than tea and cake stops, just get some more MTB shoes and pedals.
Shimano definitely more durable as said, given the potentially more hostile conditions I’d go Shimano. Speaking as a long term Keo (previous Shimano) user!
I'd probably err on the side of sticking with MTB pedals. Much as I don't like them on road, the alternative of using road pedals off road just doesn't work. The tiniest bit of mud and you can't clip in, and on the one ride I did in them I trashed a set of cleats.
Maybe try the shimano touring pedals, PD-T700? They look to have more of a flat to them than the (utterly rubbish IME) trail pedals, so might actually support the shoe rather than just making clipping in awkward. I'm tempted to get some for my CX/Commuter/Gravel bike and maybe 3D printing some shims for my shoes so they actually sit flush on the pedals like a road shoe would (or get some cheap road shoes and do the CX trick of gluing old tyres to the heel and toe).