I went off Clonidine myself and then Xanax 1 gram/daily. I was on these for two years of Clonidine, 1 year of Xanax and was on Lorazapam prior to Xanax.
Yes, the rebound with Lorazapam is worse than the PTSD itself, and I had it daily. I wouldn't recommend Ativan/Lorazapam to anyone with PTSD for this reason.
I went to my Dr. to have her help me get off the Xanax. She prescribed smaller and smaller doses for me, and checked my BP to see if it went up, which it did. I had to have normal BP and no headaches or dizziness before she'd go to the next lower dose. It took 6 months.
It is not good to go off by yourself or too quickly because of complications and the fact that a slow, medically supervised tapering statistically results in a more lasting abilty to tolerate being off. Those who taper too fast will be right back on Xanax and a higher dose within a year.
Another thing that worked for me was keeping Melatonin/B6 extended release natural tablets to help me sleep for those nights when I felt PTSD was bad.
The main support I used was fresh, 100% pure Grapefruit juice daily. Once I did that, I had no withdrawal symptoms! I believe that it does something to aid the detoxing of the body or balancing of BP and other things so that the body will not go into shock and will accept the lack of meds.
I am still taking that Grapefruit juice daily. If I don't, everyone will tell me to, because it's that noticeable! I kid you not.