Paul, I have a can of the Eastwood brush-on seam sealer that I have used in various places throughout my build, but I personally wouldn't use it for the drip rails, as I cannot ever seem to get it to lay smooth and flat.
I will admit that I am not the most coordinated person, so it may just be me. I've used the Eastwood brush-on in many places where it won't show, but I went with a good 3M self-levelling sealer for the drip rails, so they would look nice when I was done.
You may not have the fine motor skill problems that I have, and it may not be an issue for you...
