What are the problems you are having with the accesspoint?
Also, who can you connect to from there do you think? if its not likly to be more then me close by, you may be better off getting a cheap directional then a good onmi, then if anything else springs up over the other side of the harbour that you can see then you can set a second link up.
I dont hold a lot of faith in the WDS providing a massive amount of bandwidth, and the more we can move onto point to point links the better.
Some how the concept of everyone using omnis on the same channel doesnt spell fast to me.