I use both regular, and "dry" paints for dry-brushing, and i must admit i am leaning quite a lot to the side of dries being a very good, and nicely textured paint.
I cannot really explain why, but i really enjoy working with them. I get less excess paint of my brush, it dries up very fast in the actual model, and the thick texture completely disappears once the paint hits the model.
I started off with 1x skink blue, and only later got into drybrushing, now i have several and use them regularly. I can see the pro's of having them just be regular colors and have them be generally useful, but they last much longer this way, applies a great, spread out coat, and doesn't waste much paint when used.
just my 2 cents.