Solid article on variance...

[Kurn]

I remember seeing something written that compared the different skill sin poker that went something like this:

If you think the most important factor in poker is a) the significance of the important decisions, then NL Holdem is the game requiring the most skill, b) the complexity of the important decisions, then LHE is the game requiring the most skill, or c) the frequency of the important decisions, then HiLo declare is the game requiring the most skill.

In limit and no limit, you make your profit differently, so different skills are required. The one thing that is clear, is that for good players, NL has less variance than limit, and HiLo declare games only exist in home games these days.