Welcome to the site. Lots of good info here.
BTW, why the DV? They rock and roll on drift, and can't get into as skinny water as the MV. They also take more HP to cruise and therefore also take more fuel to run.
For Bay/Sound/River/Flats use, the MV is perfect. DV is generally needed in open ocean...but I doub't that you would run a 21 in the open ocean very often.