I use both a rock harness and an old decripit bosuns chair. The bosuns chair will be more comfortable, but I do not feel it is as safe (at least mine). A rockclimbing harness will have your legs feeling dead after awhile as they are not intended for sitting in for long periods. The spinlock harness may have addressed the leg issue with wide straps and padding. I climb up much like the atn with ascenders because I sail with an all girl crew two of which are under 7 and my wife would have a hard time pulling me up.
When I do have someone able to hoist me I route the line through a genoa car back to a primary winch. Much better for whoever is trying to crank me up.
If I did not have my gear, I would try the spinlock.
It's better to have your enemies inside your tent pissing out than outside your tent pissing in...