I am always using a wet palette when painting with acrylics and I can't find any cons. I am using several sizes of them. Principally they are clear acryl sheets with a damp kitchen towel and a sheet of baking paper, fixed with paper clips. The simpliest version constists of the clear part of a cd cover, the more complicated ones are custom lasered acryl sheets plus a frame, also clamped together with paper clips.
The paint is kept fresh a very long time and I really prefer this type because the paint could be toned and thinned etc in small portions beside the "central" drop of original paint. If you do that in a "deep" palette, the complete paint within this small dish is thinned/tinted.
H