With an equipotent dose of phenazepam, I actually find it more useful than diazepam. I'd rather simply consume a much bigger dose of diazepam so I can get a greater effect without fear of feeling it the next afternoon, but am low on diazepam powder which is usually more costly than phenaz powder. In truth I usually consume .5 mg phenaz and some amount of alprazolam and diazepam for stim comedowns. I still find phenazepam alone to have a heavy high that covers up most nasty comedown feelings.
As for storing it in PG, it's stable. You don't have to do anything special. I just keep mine in a drawer in a HDPE bottle, like a prescription drug would come in.