As weird as it sounds I have never watched the special editions of the Star Wars films. When I was younger I had the old VHS copies of the films, then about 3-4 years ago they released the unedited films on DVD and I picked those up. A while back I was having a conversation with someone about the worst scenes ever filmed and they mentioned a CGI musical scene added into the Jabba's Palace part of ROTJ. I looked it up and was astonished at how awful that scene was. In the end I was happy that I have never seen those versions of the trilogy.
As far as the 3-D transfers are concerned Episodes 1-3 shouldn't be too hard to convert since 99.99999999% of those films were computer generated imagery.