I have a fixed-free Formula hub so if I want to change the gearing by changing cogs it's this whole ordeal to get the lockring and cog off (I would imagine. I have not done this yet..) Plus DA cogs are not cheap ($26). It seems like a much easier proposition to swap chainrings instead. It's quick and easy to get chainring bolts off and chainrings can be had for cheap.
Just in case though, I thought I would ask: Is there anything wrong with swapping chainrings instead of cogs?