In the rainy conditions the tamiya caps on pro10 tires work very well but the caps are long gone and only a few stores have them somewhere in the basement if your lucky. They don't need full wet conditions to work but the more it rains the better they work.
The Kissling tires are rain tires that only work in full wet conditions with a layer of water on the circuit. Anything else and they degrade very easy and won't work good what i have heard from M7H.
It depends on the rubber that bsr is using on their oval capped tires. I am not sure if it is the sort of soft rubber that we want in the rain as the rubber in dry conditions is usually harder. It is purely an assumption on my part.
The video is already posted but pro10holland proved that racing in the rain is a lot of fun and really works very well with tamiya caps.
http://www.youtube.com/watch?v=InQsAw8htkY
(inserting youtube doesn't seem to work anymore?)