Hub weight isn't really a big deal on flat terrain (read: the track). Rotational matters (rims/tires), as does drag.

That being said, you probably don't want/need level hubs on the track. What happens if you need a cog at a race? Are you going to carry doubles of each cog?

If you want lots of gearing options, just get a fixed/fixed, 14+15 tooth cogs, plus a bunch of chainrings (48, 50, 52) and you'll have a very wide gear range. Plus, chainrings come off and go on with less work than cogs, imho.