I ski k2 Darksides (128 waist) with dynafits. I'm 5'9" 190lbs. Pretty much only ski them a dozen times a year here in the PNW. I skied them with Megarides for a season and upgraded to BD Factors since I felt the Megas were being way overpowered, especially on firmer snow.
However I did ski these on a hut trip this year in the Megas with great pleasure. (nipple deep conditions daily)
I agree that the boot may be a little light for that setup but the bindings shouldn't be an issue. I don't have any experience to pass on with binding swap systems though.
