This comes up again and again, the old natural versus trail cantre argument. Some people, myself included just can’t spare the time to take wrong turns and yomp through bogs. If I had the opportunity to ride natural trails with a guide, I would choose that, but spending precious riding time reading maps is of no interest to me.
My advice to the OP would be Kirroughtree on day one, Mabie and Dalbeattie or Inners and Glentress on day two. Blag yourself a friendly local from here and get a couple of days riding natural trails
on the most appropriate routes for the weather conditions and enjoy the best of both worlds.
Wish I was going to Scotland!