Jamie,
Just adding length certainly isn't going to make Wentworth a better course IMO it's one of the most overrated golf courses I've played despite being a fan of the vast majority of Colt's works.
I've only read snippets here and there and believe Els has also added about 20-30 bunkers. Overkill ?
What I read recently on golf365.com:
"The opening hole can never be called an "easy" hole, but Els has gone to work straightaway with a bunker either side of a fairway which he considered "maybe a bit too generous. It will just ask the golfer a few more questions, which I think is good".
There is more sand around the green too and so it goes on, with only one hole left totally alone - the short 14th.
The biggest changes in length come at the long fourth, which has had 54 yards added, and the par-four sixth, where the new tee is actually on the adjoining East Course and adds 67 yards."