I've not watched Dumfries extensively, but when I have, he seems to be effective primarily for his engine and physicality - and I've often found his actual touches to be quite poor, even relative to AWB (tbf I am one of the few who thinks AWB's technical deficiencies are very overstated because of some of his performances earlier in his career and his visual aesthetics). I'd really dislike such a swap. Vanderson does look a much more interesting prospect if we want to go down a more technical route.