I grew up on TUC video cassette, so I saw the extended edition quite a bit. So recently when I borrowed the DVD version from the library, I expected to miss the extra scenes, I did not. It actually was a tighter film in that regard, not sure why they added those scenes back in the first place...
As for TWOK, I've watched the DC so much that I imagine I'd miss the extra footage, as in that film, I feel it does add to the over all flow of the film.
I would love to see most of the deleted scenes from the new Star Trek
films inserted into a director's cut DVD, including the birth of Spock and the confrontation between Amanda and Sarek over how Spock's being picked on from the first, and whatever was cut out of the current movie.