I don't know where you plan on using a drift boat, but for the Delaware you don't need one, my buddy had one and it is back breaking work to fish the Delaware with one.
A friend who many of you know, has jet motors on rafts and he's been guiding on the river since the 70's. On holing in current, it's easy to hold using anchors or an anchor, you have to pick and choose where you anchor wisely though. What we always did was pull over and wade where the runs and riffles are, yes there are places you can't wade to, but they aren't that many.
As to faster rivers, you still mostly get out and wade anyway, because it's dangerous to anchor in current with a drift boat.