I ran 1e-drifted 5e and 1e parrallel for a while in the same setting. I found I mostly preferred 5e, mostly for the magic system. I like how 5e does monsters, too. I find it much easier to drift 5e than 1e to what I want.That crunch isn't the only thing making AD&D feel like it does. The emphasis on a particlar sort of skilled play is very different from 5E. I agree that 5R E is quite flexible, but in this case it feels like reinventing rhe wheel when you already have thatbwheel on your shelf. YMMV.