Oh, my... five coats and that's all you got? Are you sure the paint you have is fresh? How thick were the coats?
When I use paint, I place drops of paint on the surface, using a toothpick. Let the "blob" of paint dry, and then add more where I see the glow is lacking. It doesn't make for the preeeetiest finish (definitely not up to darkzero standards!), but it works well in the glow department.
I used paint almost exclusively for mods behind optics, where the rough surface can't be seen (but the glow shows through). Plus, I feel the paint's adherence compared to the epoxy+GID mix we use is not as good, so putting the paint behind the optic is another way of protecting the finish.
The main use I have for paint (water-based) right now is for painting star fields on ceilings. You load a syringe with GID paint and push a small drop out of the syringe and touch the ceiling with that. A little "dome" of GID paint sticks to the ceiling. With practice you can make domes of different sizes that mimic stars of different glows. It's pretty fun - my younger kid absolutely loves it, plus his whole room sort of glows all night.
I don't feel the difference in glow is significant between the v9 and v10 powders. v8 is a little dimmer, but still has worked well for my needs.
Hope that helps a little.