You've identified all the issues. The final decision is not an easy one, but much of it hangs on the total cost, and what that means to you.
The 7D body is available in the US online for around $1500. You'd probably want a spare battery, but all your lenses fit. I tested a 7D from CPS when it came out, and it's a very decent camera. High ISO noise was not that bad and could be controlled in raw processing. It handled well, and was very quick to shoot and focus.
The 5D2 with the 24-105 is closer to $2800, but much of that is the value of the excellent 24-105mm lens. I finally purchased one this winter when the prices kept dropping to the point where it made sense for me to buy one for personal use. I had the same lens issue you do, owning the Canon 17-55/2.8 EFS lens, so I needed the kit with the 24-105.
The 5D2 looks almost exactly like my 40D cameras, which is reasonable considering they came out around the same time. The 40Ds are nice, but I was never really in love with them. So I was expecting to find the 5D2 to be a nice camera, but not really love it -- especially after listening to years of complaints about the AF system. However, I am surprised to find that I really love the 5D2 and use it for almost all my shooting now, both at home and at work. The AF is reasonably quick and accurate (now that I have completed the micro adjustment on all my lenses.) The full frame viewfinder is wonderful, and the 21 megapixel files are smooth and beautiful. I for one am glad that I waited to buy this kit instead of getting a 7D, even though the cost was almost twice as much.
Not sure how to handle the long lens magnification effect of the 7D versus the 5D2. The 300/4 is an excellent lens and works well with the 1.4x TC. Not sure if that is long enough for wildlife, as it's not something I shoot. I can say that the files from the 5D2 crop very well -- even cropping away half the frame gives you more to work with than your 30D....
Good luck and have a great trip.