I tried to find my old reply about my Xifaxin use but couldn't...maybe I'm just not typing in the right thing.
Anyway...here's what I can remember (I really should have kept/should keep better track of things but as I was getting better I was too excited to think about tracking things).
My doctor thought I was steroid dependent (couldn't make the pred drop from 20mg to 15mg without flaring). He wanted me to go on Imuran or Remicade. Due to a family and personal history of skin cancer/precancerous cells I argued that there must be something else I could try. He said that Xifaxin was still pretty new to UC but I could try it and it had worked for some other people. I was on it for approx 60 days and was able to make my pred drops down to around 7.5mg while on it. I then went off the Xifaxin and was able to make my way the rest of the way off of pred without having to go on any new meds. I'm currently in remission and getting back all the strength I lost with my first flare when I was first diagnosed 10 months ago.
Xifaxin was definately an awesome drug for me. 
I was more gassy with it...but I also had more energy and better mornings while on it. Just the fact that it allowed me to get off the pred w/o going on anything stronger made it totally worth the cost ($150/month co-pay).