One can argue Luke diverted the Emperor from supervising the battle more closely. And nobody but the Ewoks knew about the back door to the shield generator did they?

Yeah, I remember the ROTJ novel made that point. I think Han said something about “Luke keeping the Emperor distracted” which helped me see the whole thing a bit more favourably at the time.

Ultimately I wish the Vader/Luke/Palpatine scenario had been somewhere other than the Death Star (perhaps on a Star Destroyer bridge). That way we could claim outright that Luke defeated the Emperor while the Rebels took out the battle station (rather than assuming that Luke and co. were going to be blown up anyway). That would be a worthy legend, irrespective of the details regarding Vader.

I see what you’re saying though. Thanks for the replies!