OK SN, in the interests of the discussion ( and please let's keep it a discussion and not a slanging match) , I've found an FAA approved fright manual for the 502 dated Oct.15 1996 and scanned through for details on use of condition lever in flt and during landing plus use of power lever behind the gate.
Fistly the condition lever on landing,
Under NORMAL PROCEDURES, sub section APPROACH AND LANDING( NORMAL-EMPTY HOPPER) ;(won't bother with all the points).
2. Start lever S- Flight Idle Position( 68-70% Ng)
(this was a point insurance companies in Aus' were keen to highlight a few years back)
On use of power lever through the gate in flight I could only find the following reference under Emergency Procedures, sub section ILLUMINATION OF CAUTION LIGHTS(AMBER).
Prop in Beta Range: Indicates prop' pitch is at or below the
minimum fine pitch that is safe for continu ous in-flight control. During ground opera tions it indicates prop' is positioned for ap plication of reverse thrusting power.
The way I read that it's a cautionary indication based on aerodynamic considerations (quite true and demonstrably so with over-eager fistfulls of beta in flight) not a powerplant engineering matter, if it were a possibility of being unable to come back out of light beta in flight I'm sure something more impressive would be mandated by the FAA.
BTW I agree that landing in flt idle without using Beta will most definately result in long floats in ground effect, which tends to make the case for light Beta even stronger.
I guess we'll all keep operating the way we are so long as everyone's happy.