Totally depends on situation for me.
If Dak is signed, and my list of starters (ie CB maybe LB) are gone, then yes I would probably trade down -- even with WFT.
Would I do it if I thought he was a franchise QB -- nope, I 'd draft him and use him later to eliminate any leverage or trade him for future picks.
If WFT wanted him and all my criteria was met, it would cost them swap #1, a #3 and next years #2 at a minimum. Hefty price for moving up 9 spots, but worth it to me, and worth it to them if he really is a franchise QB.
The QB leverage statement.....I think Dallas should draft a new QB every three years regardless of the situation. IF you can develop them, then they become great trade pieces later. I am sorry if the QB's of today don't want real competition, produce and you won't have to worry about it.