I'm practicing rapping using a skinny tag line and a regular fatty lead rope. This is a 7mm and a 10mm. I had no problem rapping the regular way with an ATC. Just had to go a little slower. But, if you want to use an autoblock knot, you need at least one more wrap around the ropes.
t's even necessary to clip to the fatty.) When I got to the bottom, just pulled the skinny and voila. Both ropes pull easily. The big 'biner might get caught, so you have to be a little careful. But using a skinny instead of two fatties would save a lot of weight and space.