Yes, there are some small changes. As an example, here is the antiphon O Sapientia (December 17) from the 1934 Antiphonale Monasticum and the 2010 Antiphonale Romanum.

What, what???

Atrocity!! (someone had to say it)

What I find interesting is that neither melody here matches the Liber Usualis. Oy.

I really don't think it matters which version you use. Obviously the newest versions are based on the most recent research into the chant manuscripts, and so the ultimate goal of such research is to arrive at the most accurate reading. If you've never been doing Advent Vespers before, I say you should use the new ones. If it's something you've been doing for years, and your schola is used to the old ones, use the old ones. Do you think anyone would really remember all those little details after a whole year, though?

The 1934 Antiphonale Romanum Monasticum is ... on-line somewhere... Hm, where is it? Anyway, it's not the latest editions; the newer Solesmes books are only ODT (on dead trees).

That's a good point. I don't mind purchasing one copy of the book, and I probably will anyways. But I can't afford to buy a copy for each member of my schola especially since we won't be using it that often. If anyone happens to have a clean copy of the O Antiphons that they can post that would be great.