I really, really hope they update it to full 3.5 rules. 2nd Edition is really obsolete and inflexible, and it's a pain to go back to it after this long. I haven't played with 4th edition personally, but I listen to a lot of podcasts about it and it doesn't seem like it would fit well with the BG series. 3.5 seems to be the best fit. I would love to be able to replay the BG series as an armored mage.