I seamed sealed my mitts with a tooth pick also. Made it easy to put just enough sealant where I wanted without spreading it out all around the seam. I found it easy to do, but I don’t mind doing detailed work that requires patience. I think many that have troubles, are trying to rush it too much in order to get it over with.
However, I didn’t originally seal them for the PCT; I did it 2 years later for the AT. On the PCT, when hiking in all day rain, I found that my hands would get damp, but I half suspected it was a much from sweat as anything external. In any case, my hands were always warm which was the important thing. Not sure if it really made much of a difference since I had a similar experience on the AT after they were sealed. But the mitts were well used by then, and the AT was much wetter. Overall, I still was happy with warm hands even if they were damp.