I've got a few minutes flight time in a JetRanger, but that's about it. Did okay, though, circled around an airport, and understand the cyclic and collective. Hadn't tried hovering, though.
I would expect you'd want a bit more than that.
That's because in fixed wing, if something goes wrong, you've got a glider and can usually trade altitude for time while you try to sort it out. Rotor, something goes wrong, you've got a crater... Altitude then becomes a liability, as the more altitude, the deeper the crater.
Not necessarily, you can autorotate. You're still going down, but survivably. If you're over the ocean, you're going swimming, though. That's why Coast Guard sorts have those breathing air bottles in their vests, so they can get out safely.