I would advise caution before trying this. An airline I used to fly down the back for had a thing about getting the pax off as quick as poss. It worked OK until one day, for whatever reason, the other system didn't kick in and the with no brakes to stop the a/c the other prop chewed up a GPU before the a/c stopped. After that all engines stayed on until you stopped. Some years later when jets were introduced the policy was reversed to shut down the left hand engines again to get the pax off quicker. Sure enough within 18 months the same thing happened again, this time with an engine and pylon striking a jetty. It doesn't matter what the reason for the hyd. not working was in either case. If the proceedure's right it takes away the risk. At the end of the day I suppose it's a judgement call. Does the benefit outway the poss risk?