I thought about fitting a sprung ball bearing valve but couldn't reconcile the risk of a stuck valve to the engine. I have fitted the kingpin awsv. Works really well, the switch is very well made and it has a reasonable amount of friction when you turn it. If it is mounted so that it is open when turned downwards it us unlikely to move when the engine is running. I have used 'test meter' (ultra flexible and strong) wire with crimped and soldered connections for the switch connections. I also clip on a 'remove before flight' tag when its in the off position. Also check return oil flow is good whenever I start it. A lot easier than undoing the sump plug and draining. I guess you choose the solution that you feel most confident with.
