I can't claim to have all the experience since I'm fairly recent on the Mighty Electra as an engineer working for the UK based cargo airline.
So far I've had the pleasure of sitting along their aircraft a fair few times now but all I end up doing is yawning because the mod they did has taken all the necesity out of having a FE onboard. And to be honest the difference in quality of maintenance you can get out of a travel weary FE compared to a well rested engineer waiting on the ground is not to be underappreciated.
And I've even had time to see my first apparent (it was gear box) engine failure and the pilots didn't get particularly upset about it. Very well managed indeed.
Sure, the FE fills a purpose but to say that it's dangerous to fly without one seems, to me, to be a stretch.
I'm very curious to see what happens with this new venture though. The Electra is a lovely aircraft and deserves to be in the sky, not retired.
That's my 2 cents...