Spin up is a function of inertia - since hubs affect inertia very little, it has to do with rim and tire weight. At higher speeds it also has to do with spoke count. Aero wheels don't necessarily spin up faster - they just keep accelerating.

An FYI - one cannot tell how good bearings are by spinning a wheel while holding it in one's hands. That measures, among other things, bearing seal drag. Spinergy had excellent bearings when they started, but when Mavic came out with wheels that had poor bearing seals (and therefore "spun better"), Spinergy had to react. Against the wishes of their engineers they eliminated the bearing seals. Suddenly Spinergys were "fast".

A similar myth surrounds derailleur pulleys. If you get a cartridge bearing pulley and spin it with no load, it'll probably spin slowly. A bushing pulley should spin pretty well. A loose bearing pulley spins pretty well too, the nicest really (Campy). But put a load on it (i.e. chain under tension) and suddenly that cartridge bearing pulley works really, really well. Put 1000 miles on the drivetrain and that cartridge bearing pulley will now pull ahead of all of them. Even the loose bearing Campy pulley slows down when it's dirty.

So a "spin test" is not a test of mechanical advantage. It's a test of how the wheel feels when you spin it in your hand. Nothing more.

A properly adjusted round bearing surface hub is pretty equal to other properly adjusted round bearing surface hub. I include "round bearing surface" because the 105 loose bearing hubs (and lower) all had oval bearing races and could not be adjusted. Only the machined bearing surface hubs (Ultegra, Dura Ace) were smooth consistently. Since bearings make so little difference, I basically ignore them. If a bearing goes south I'll just replace it (since I have pretty much all cartridge bearings in hubs/BB).

Hub shells, other than weight and strength, also make no difference. I want a wide flange for lateral rigidity. The Mavic hub of yesteryear, while beautiful, made for a super flexy wheel. I imagine the same will hold true of narrow flanged hubs by anyone.