I like having McDiarmid there as a visual continuity match to the rest of the series, but I can't say I liked his reading. The difference in his delivery between TESB and ROTJ is annoying (though I do understand it; it's been 20 years since he did ROTJ); he sounds like he's half-asleep! And yes, that "enhanced" dialog adds nothing to the scene other than an unnecessary link back to the prequels.

The technical challenge of overhauling this scene while keeping McDiarmid in it (I'm sorry, but I can't see going back to monkey-face) would seem to be insurmountable. If Ady can pull it off, he'll truly be a Ghod Amongst Ghods.