I am rebuilding an old bike so I was taking the tank off a lot and it was a pain disconnecting the crossover tube under the tank. For that purpose, it is indispensible. Unfortunately, its also not cheap, but it is well made, so its worth it if you need it.
I actually use the fuel line connector for my brake point on my hydration hose.Since the hydration couplers I searched for did not stop the flow of liquid when detached I substituted the fuel disconnect coupler. The port is a bit smaller than the hydro units but I still get plenty of cooling flow on the trail.