Your decision depends very much on what your end goals are.

I left my job as an 121 CRJ FO for a part 91 Citation job before Thanksgiving. I had 2400 hours, 1400 jet with a little previous turbine 91 experience and was hired into the operation as a captain. The job was in THE location my wife and I wanted to move in, with compensation equal or better than 50 seat CA pay, for a small but financially-sound company with a new airplane on firm order.

You state your ultimate goal is at a 91/91K operation. Fractionals love airline FOs but only if you have an ATP and (at least) 2000tt. If you want a pure 91 job you'll probably need a job to wash off your "airline stink", and a 135 operator is a great way to do so. That said, with your TT being only 400 hours you need another 900-1500 hours before you make that leap, and in your current job that's probably 12-18 months away. Some 135 operators LOVE to hire super-low time pilots and throw them in the right seat with little training for very substandard compensation, if for no other reason than because they can and the candidate often doesn't know any better.

My advice would be to stay at the regional and fly as much as you possibly can, and start/keep networking in the 91/91K/135 sector. If still interested in a charter or corporate job, start sending out resumes at 1200-1500tt but you'll probably only be qualified for an entry-level copilot job with that amount of hours. At that point it might be beneficial to you to make a "lateral move" to an entry-level Citation or Lear copilot job if the QOL improves for you and it positions you closer to your ultimate career goal of driving bizjets.

Good luck...