I'm interested in this as well as a way to get away with upgrading the cross bike. Kinda sick of how it is setup now.
I could see it working. I run a 50/34 on my cross bike and use it for gravel riding. The 34 is plenty in any cross race I've done with an 11-32 cassette and clutch RD. The crank was just what I had laying around to fix it up to be 11spd instead of be 10spd.
I agree on the mtb in cross thing, to start out. I feel locally there's guys who are winning that need to back off and get a dang cross bike. They abuse the generosity of the rules a bit IMO. They run the barriers a bit low here, so they just freaking bash over them on the mountain bike like nothing. It's cross, not mountain bike race. I think they should only allow Cat 5's in the 4/5 races to have mountain bikes. Not the cat 4's always in the top 5.