You know it's dark days when GWS starts busting out the puns.
I had Stamps make me the same board but one with single con, one single to double. The single felt like it had a little more forward projection, a little more spark in small waves. This one didn't have the tendency to be sticky but I have felt that sensation in some single con boards, especially when the concave is deep and goes too far forward. The single to double Tim makes is an inset double. Compared to the single it felt like it rolled onto rail easier. Less zippy, instant speed but more stable and predictable. Felt more stable at speed so had a little more upper range.
My favorite bottom contour or at least the most consistent, just looking back at all the boards that I've liked the most, is probably a fairly moderate single to inset double. If the board is wide and flat, some vee off the tail doesn't hurt but for a shortboard thruster type board I don't like much, if any vee. For a Twin it can be good because it feels like it gives somewhat of a center point but for a thruster it feels like just amplifies that center fin effect and feels too planted. I don't seem to like boards where the double concave is extreme and begins too far forward near where my front foot is placed. Maybe for people with a different weighting bias it would work but for me they have felt slow and unstable.