You could leave light and heavy slash as simple /ac's when auto attack is implemented. They're no different than weaponskills, so whatever they do to ws's they can just do to them and keep them.

I love the idea of being able to continue damage and TP build while you're waiting on the BR to finish. Ancient magic was designed that way. A lot of our meleers are getting hamstringged by the regimens a bit because they're not acting. BR still does more damage than if they just used DPS rotations, but it'd be nice to maximize their TP and damage outside the regimen.