I like the De Santis "Apache" ankle holster.

I have used the Glaco and it was pretty bulky on the ankle. I have seen people try to use the Fobus and the kydex makes it super bulky. The boot lock one is ok but then you always have to use boots and it is slightly bulky too.

So the best one I have found is the De Santis, it is light and comfortable. It does not seem to spin around on my ankle as much as the Galco did either. It pretty much stays put. It may look cheap and cheesy but give it a try and see what you find out. I wear it with both boots and shoes and it is comfortable either way. You will find though it is going to be much more comfortable with boots.

And no I dont think that the above the calf strap is needed.

Sweat is a problem with any kind of holster and gun. You just have to maintain your stuff so it doesnt break down on ya.