I understand your thoughts. I agree the lightsaber rebuild on Tatooine works fine. It's the Degobah scenes that suffer, imho, from not having the benefit of time spent in training.
The Degobah scenes as conceived are essentially stuff that could have been handled with a phone call. If only Luke had Yoda's number he could have asked, "Two questions: is Vader my dad and am I a Jedi?" "Answers to your questions are: yes and no... Vader. You must face Vader."
I have to say I was amazed by the effectiveness of the rough edit in this thread that panned down to Degobah from the crawl and showed Luke in training with Yoda. THAT is what I wanted ROTJ to start like. Then Vader hunting Luke. Yes! That's what this movie was supposed to be about. It feels to me like you have the ingredients of a miracle there, but I don't know from vfx and can only wish it were in your power.
Regarding the Ben scene, I have always disliked it as well. But in the placement where it would fall on Endor, it actually brings a narrative boost-- just when Luke needs to see Ben. I would venture to suggest a version where Ben says something new, recutting what is there to work with. I think it might be that he hints at Leia's relationship to him and then Luke puts it together, or Ben avoids the subject altogether.
The thing about that scene is that "from a certain point of view" is just bad logic. That might be a saving grace if that flawed logic were presented here, as Luke prepares to face Vader. Ben's words are small comfort and really do nothing to prepare Luke for the Emperor's tricks-- they may even plant doubts. If that's the way you play it (with music and editing) -- this could be good. In essence, it would be a scene about how Luke is so low because even Ben has become no help to him... dark, dark times indeed.
This suggestion is made also in light of the opinion that the Luke/Leia/Han scenes there in the Ewok village are pretty clunky in concept and hurt the flow of the story. I think Ben showing up is surprising. If his arrival can be given story weight (i.e. he tries and fails to bring Luke comfort before battle) then it could be a good idea.
Sorry to be pitching you ideas you have already discarded. I realize I'm doing that and can only hope you see I'm not trying to be argumentative.