One thing to remember about sealers on concrete, if you paint the pot in a color you want to preserve, say you paint it red and you want it to stay a bright red, then a sealer will help preserve the bright red color. But if you want it to become more aged looking, then don't seal it and the paint will take on an aged look.
The other thing to remember about sealers on concrete or terra cotta (clay) pots is that sealers block the natural dehydration process of porous pots. Sealers keep the concrete or clay from breathing and the soil will stay wet or damp longer because of the sealer. Paint alone doesn't seem to have that same affect unless you've covered it in multiple coats of paints.
Just my 2 cents worth this morning . . . says she who hasn't yet had time to make a cloth and concrete pot. Yet. But I do know about paints and sealers.
