I have only had my set up for a couple months, so take my advice with that in mind, but I would say go with the 3000. As the others have said, the 2700 will work on 4x8 straight cut, but any angles will make it too short.
In my case I went with the 2700, mainly because I did not do my homework. I was unaware of the 3000 and more importanly I did not consider the parallel guides and their need of that extra length. Now, as I prepare to purchase the guides, I have to either sell the 2700 rail or buy both.
Quite simply put, the 3000 will do everything the 2700 will do, but that doesn't work in reverse.