ErgicMergic
Bluelighter
I can actually imagine benzodiazepines enhancing the depth of a psychedelic trip, simply by allowing one to feel more comfortable pushing the dosage higher. You might take that extra tab / hit / 5 mg, if you knew that the potential anxiety of the trip would be muted somewhat by the security blanket of benzodiazepines.
I think the only reason you can push the dosages higher is because benzos dull the psychedelia of the trip, making 5 hits of LSD under the influence of benzos equivalent to 2 hits of LSD benzo-free (just an example, not sure about how much benzos dull the trip).
To be honest, stay away from benzos during the trip. If you absolutely need benzos, then you're probably not in the right state of mind to be dosing psychedelics in the first place. Instead, carry a benzo around with you while tripping as a safety net/panic button. Some find that just having some sort of safety net in their pocket makes them feel better while tripping, and some find that's enough to relax them without even taking the benzo.