Is there anything wrong with the Armalite float tubes? (Other than they cost more than others)  I like the way it looks and want to put one on a varmint rifle.

I have a armalite float tube on a 20" barreled upper.  I think they are very good, you can reuse them with no problems, easy to index the tube,  they are a bit larger in dia - they fill your hand better in my opinion - would be nice if the tube had some kind of grip surface - they feel just a bit slick  -  but you could put some kind of grip tape on the tube if that is a problem.  I shoot mine off a bench once in a while so it is nice to have the smooth surface for the rest.

Hogue makes a real nice free float with a rubberized surface. If you have ever owned one of the grips you will not use anything else. This is comfortable in your hand and does not get slippery in damp weather.