I'll have to look for other cuts. Most of what I would suggest happens already in the DanEdit, so if you like anything there, I say go for it (with appropriate thanks).
As for upping the tension as Luke and Vader talk, it's mostly simple. After the SuperStarDestroyer crashes, the original cut goes inside the DS2 where everyone's panicking and running for cover. This doesn't make obvious sense-- sure it's bad news, but the crash shouldn't affect the DS2 one iota.
So cut instead to Lando and Wedge going into the DS2, follow them all the way to the center-- there it is: WOW. Let's hit it. Wedge blasts away and something blows up.
CUT TO: inside the DS2 where everyone's panicking and running for cover. See Luke carry Darth to the ramp of his ship and collapse.
CUT TO: Lando flying in for his attack run-- he blasts the reactor and it starts to collapse. We gotta get out of here!
CUT TO: Luke and Vader -- they talk and the tone is somber-- but added sound effects make it clear that the DS2 is collapsing from the inside. Distant explosions grow louder and more constant. Luke doesn't care, he's going to have this moment. He reluctantly agrees to remove Vader's mask. He takes the top off...
CUT TO: Wedge flying out of the DS2. He's safe, but what about everyone else?
CUT TO: Luke pulls back the final piece of helmet (only need the last bit of this footage) revealing Vader's face-- they see eye to eye and talk. Vader tells Luke to run. No, says Luke. Vader dies.
CUT TO: Lando flying deep in DS2, flames coming fast behind him. They eat the TIE fighter behind him.
CUT TO: Luke's ship in the hanger, moving as the hanger falls apart.
CUT TO: Ackbar orders his fleet to move back.
CUT TO: Luke flying out of the DS2 (Maybe lose his last "sigh of relief" which is strangely unconvincing).
CUT TO: Lando completing his death-defying escape from the DS2
CUT TO: DS2 from a distance-- it explodes.
MAYBE: after the explosion is the place where we should see Luke's "sigh of relief"? I don't know. If it were a better performance, I would say we need it. But I just don't know
That would feel a lot more tense and sensible. In the original cut, it takes longer for Luke to load dead Vader into his ship than it does for Lando to destroy the main reactor and navigate all the tunnels out from the heart of DS2.
Plus, to me, it will add emotion to Luke/Vader's scene when we see how they're risking death to have their final moment together.