This is my experiance, when we tried using a storz connector on a standpipe to draft we found the gaskets are designed to seal using internal pressure. When a vacume was introduced the gaskets leaked. There may be another style gasket for this purpose, but I am not aware of any.
After my 1st post I checked into it and found out there are gaskets specific for suction. I'm glad I saw your question, I now know something new, and another option for us since we're concidering storz on our hydrants.
we use storz on our hydrants and it makes things alot easier in case of a busted hoseline. just recently we had a civilian drive over our 5 inch during a fire and busted it, in less than a minute we had the length of hose replaced and our water supply restored
We use Storz connections for dry hydrant and dump tank drafting operations. The gaskets must be matched and for suction/vacuum purposes for best results. It is also important to connect the Storz side prior to the threaded side if using a low level strainer that is not preconnected. Attack pumper set up with a dump tank using Storz connections with preconnected low level strainers on the hard suction saves considerable time.
Also be sure to maintain your gaskets to extend the life of your fittings, we wipe a small amount of grease on ours to keep them lubed. Grease also helps to form a seal when using in the vacuum capacity. We draft with them and haven't had an issue yet.
Pro's - easy and fast to connect, either end works, typically no rubber mallet needed to tighten but they are not as easy as a pressure type storz connection (like on supply hose). You MUST have suction gaskets, they have the raised 'bump' on them. Captain Nick above recommended greasing them, I agree - use a waterproof grease that is compatible with the rubber gasket material.
Con's - no matter what, they leak air and you risk loosing suction. We carry a roll of duct tape and just put a wrap or two around the connection, works great.