As someone who has done five WEEKS on/five weeks off (in theory, reality even worse) a 15/13 sched would be a piece of cake. I can easily see how the guys on the 15/13 like it so much. One gets used to frequently having a long period of time off.
As stated above it's not for everyone, but if you have a patient wife as I do, it's quite nice. With kids in the picture it may be different, but the good thing about it is that one can always switch if it doesn't work out.
SS