I use dr. bronners in a foaming handsoap dispenser. It is refilling a bottle that originally had another brand of castille soap (ballard organics). The ratio for mixing as given on that bottle was to put in an inch of soap, and the rest water. It won't clog.
I don't find it drying at all. We use it as hand soap at all of our sinks, so I wash a lot.
ETA: these are what the bottles look like.
http://www.ballardorganics.com/inc/sdetail/3025/3028
L, mommy to my one and only, super-sweet boy, G 6/08
I'm pro-big bird, and I vote.