Here in the mid USA it gets pretty humid in the summer and I really don't have a problem with moisture in the lines. I get a lot of water out of the tank when I drain it but I've never had problem with it at the point of use. I only use a dryer on the one outlet that I use for painting.
Skiddy - from what i have read, the water in the air after its compressed is hot (of course) the water is in vapor form when its like this. The compressed air needs to cool for the water vapor to become water again, if you are using lots of air, it doesn't have time to cool as its being used up as fast as its being generated. This is where you have problems with moisture, if you can allow the water to cool off before use its pretty dry.
From what i was told by a guy that gave me a long length of 1 1/4" bore hose said its shouldn't be used for sand blasting (which i'm using it for....) because this style hose when air is passing through gets hot due to friction, friction generates heat and any moisture in the line us kept in vapor form. For sand blasting you really need dry air or the sand clogs the nozzle, so its a big concern.
For general use, simply draining the reserve tank is enough and installing a drier/water seperator at the end of the line when painting.