We are both using the 160mm and have been happy so far. I've not looked into up sizing so I couldn't tell you if there is clearance or not. Yes, the Nashbar one looks like the same fork.
Re. the crash, I remember seeing that site before. Correct me if I'm wrong, but didn't the fork failure occur due to a quick release popping open? Looked like the guy crashed a nice Calfee too didn't it? As Mark has stated before, disc set ups aren't for everyone, but then again, neither is flying down a hill at 45mph plus on a tendem!