In the last map party I was in, we did ~3 maps per person, six people. Three gave 1x Thav Leather, one gave 3x Thav Silk, and one gave a Bluebird (didn't even know that was a possible drop!). Five rare drops out of 18 maps is pretty darn good, if you ask me.

RNG is RNG. I don't think the rate has changed.