An unconnected gate on a FET is ON. An unconnected gate on a Transistor is OFF. They get activated with a whiff of any stray voltages or radio. Just from the stray voltages from powerlines, a FET would be on if the gate was unconnected. Clearly, an unconnected anything is not a good circuit and no one would create that deliberately, but the failure mode of both is Dangerous for FET and Safe for transistors. (I'm overgeneralising here, but what I've stated is true in principle) As a plus, implementing current limiting with a transistor circuit is easier. However, using FET SHOULD result in lower power dissipation. Like most things in life, there's a tradeoff has to be made.Wasn't about the circuits shown in the thread. It was about your comment concerning a trend in using FET devices which Grog6 followed up by saying it isn't a good idea. The reply from kc9qzf and I agree with is a launch controller using FETs that is properly designed for using FETs is practical.
And to say it one more time, there is not a properly designed circuit shown anywhere in this thread.
Looking forward to when @kc9qzf gets back to civilisation and posts his version.
My 2c. YMMV.