I think I remember saying the 66 might be the size for you but the 71 would be good if you often sail a bit underpowered. The 66 prefers some speed. So you got a 71 and now want to change? What do you feel are the limits of the 71 (always good with some feedback).
As for the question? Yes, the 66 supports 4.7 and even 5.0. It's actually early planing and goes upwind well, the downside is more that it prefers a bit more drive an speed when wave riding, but on the other hand it's super precise and smooth when you have the speed.
I think the Quad 66 actually has 65 liters, so it's not bigger in volume. And it kind of narrow too. But I don't know the other boards you mention well enough to compare.