Have been using the raven concealment eidolon for a couple months and it is very comfortable. Before that I was using a bladetech nano and it was okay but not really designed for appendix.
You'll love it. I've been wearing it for about a month or two now and its great. I'm starting to transition to the 4 o clock position a little more frequently so I'm probably going to pull the trigger on a NSR C4 as pretty soon as well.Just ordered this exact holster for my 19 last week. Can't wait for it to get here and try out!
All my IWB holsters are Phlster Skeleton (G19, G30, M&P Shield) which are chiefly designed for appendix carry although I rarely carry that way. Skinny or not, for the life of me I cannot see how people sit down comfortably while appendix carrying!
http://www.phlster.com/
Move it closer to the center if you have it over by 2, and loosen your belt some. It doesn't have to be cinched super tight to hold the gun up like it does when wearing it at 4 O'Clock. That lets the gun move up and down just a little to move with your body, like when you sit.
So its right over your Johnson? Never tried that.