I can't comment on the vinyl since I am not a vinyl guy at all, but I do recommend picking up the Making of SFaM official bootleg, especially given that it's your favorite DT album. To answer your question about the album version vs. the original mix, there are some differences for sure. Through Her Eyes in particular is the most different, if I'm not mistaken. There are differences in the rest of the songs, but that song is the most significant.
But I'd also encourage you to pick it up for the first CD as well, which gives you an idea of how the album was put together, the writing stages, etc. Some pretty cool clips of them working out the songs, and especially within the early stages that include some ideas that were either modified or completely thrown out.