Yes, benzos totally wipe out POIS symptoms entirely for me. Or 95%+. They last 3-4+ hours and I don't take more than 1 a day anymore. Tolerance builds up really quickly with them. They feel great. Millions of Americans are totally addicted to Xanax or benzos. Doctors hand them out like candy. If you're very disciplined, responsible, and keep track of usage, take breaks, and don't allow tolerance to build up by taking extensive breaks if tolerance starts to build up, then it may be an option for POISers for emergency use. That is how I try to use it now - emergencies only. They are a miracle drug for that purpose alone, and a total curse if taken irresponsibly or on a regular basis for long periods of time.
Diazepam I tried a few years ago but tolerance built up after the 3rd or 4th time I used it so I stopped. It gave me 5 hours of relief per 2 mg pill.
Xanax started working at 0.25. Had I taken extensive breaks as tolerance built up from the start I would still be on 0.25. now 0.25 does almost nothing for me. 0.5 is where I'm at. I was at nearly 1 mg once per day, but after taking a break for 7 days, tolerance reduced to 0.5 mg, and now I am trying to taper from there to get as close to 'normal' as possible.
Good luck...