The Six sounds like a good deal. At your size there should be no problems with any frame you may want to own.
This is the first I've heard about 105 shifters and cable problems. Part of the referenced thread seems to indicate it could be an issue across all three lines of Shimano shifters. It also sounds like set up and maintenance can reduce the issue.
I jhope it's not as bad as some indicate. I have a set of near zero mile 105 shifters to go on my "new" bike along with the remaining Ultegra bits.