Dan,
I agree losing 17 would be a big problem. As a whole I think 16-17-18 is a much better finish than 7-8-9, where although the holes are good holes, there is not quite the same demand on your game as is the case with the current finishing holes.
1 would work as a good 10th hole, but I don't think 10 would be a great 1st hole, because of the OB on the left.
Jason