Gabapentin will make the benzos hit you like truck. It really isn't as dangerous as alcohol and benzos as gabapentin causes minimal cns depression.
Start out low as always, take and cur your doses in half for each...like if you usually take 1mg of xanax alone, take only .5mg with gabapentin.
Also know that benzos increase gabapentins bioavailability while decreasing the benzos bioavailability....usually I would take gabapentin allday and wait atleast 1hr after it to dose benzodiazepines
Yah it might not be the best hr advice to tell you it won't be bad to mix the two, but as long as to stick to low doses, don't drive, have someone watch over u during the experience and especially don't drink you should be fine.
The most important part is if you have a tolerance to both gabaprntin and benzos you should be fine, if you have never taken benzos or gabapentin, or if u have only tried one and not the other, don't take them together!