As the resident shock expert here... I'm going to have to respectfully disagree. Air shocks, while ugly, are the most versatile shock made. Just by the design, your spring rate is almost endless. If you are unaware, shocks are filled with nitrogen. Nitrogen does NOT react to temperature/elevation/humidity, which is why the majority of tire shops are starting to fill tires with nitrogen, not to mention nitrogen doesn't harbor moisture the way oxygenated "air" does. Having worked around shocks for the MANY years I have... here is my suggestion.
If you only do one type of riding, ie trails, dunes, rock, whatever... get the Elka's and set them up for what you do. If you want to be able to adjust your shocks easily, and almost "on the fly", the floats are the way to go.
Typical coilovers WILL give you a better all around ride, but unless you are competing, I doubt you will notice. Air shocks are AWESOME products when used correctly in the right application. There are very few scenarios that an air shock, such as the Floats, WOULDN'T work well.
If I were in the market for shocks, I would get the floats just for the adjustability factor. I think I'd like the options of HAVING so many options (if that makes sense). Parts are readily available, and cheap.
In conclusion, as far as spring rates go, the air shock is BY FAR the most versatile option. You change your spring rate by the nitrogen pressure. Most Fox's (not sure about the Floats), can be pressurized up to 800psi in case you're a fatty and need a 550lb spring rate. =)