Don't do it. I left XJT for a charter gig and look forward to when I can get back to 121. Ever since I left I have such little control over my schedule.
135 regs only require you to have 12 hard days per quarter. Or something similar... maybe 14 days per quarter. It is such crap. Even the months that I had 8-10 days off, I was still on call, so it's not like you can go anywhere... ugh. I know I am starting to sound like a broken record, so let me say that there are some good things from 135/91... I just miss jump seating and hard days off.
Anyway, sorry for the tangent.