Another wrinkle I failed to mention: I would like to carry over my dynamo setup from the previous bike. The disc frame is a thru-axle (QR15). That would mean buying another hub. The "cheap" option is like over 200 bucks just for the hub, plus a pretty penny for the rims and spokes. I can build them, but still.

I'm starting to think budget and timeline might be the deciding factor here. I could always build another disc bike in the future.