I have a Felt Z-70 and the main difference is that the components are 105's (good stuff) and the frame is aluminum except for the seat stays and fork, which are carbon. I love the bike and the carbon seat stays made a ton of difference in the feel over straight aluminum, but other than that it's supposed to be the same geometry as all the other Z frames, only difference is in the components. Upgrade the components and it's basically the next model up except that it's all carbon and a ton more $. From what I was told, unless I'm riding Cat 1 and am one of the chosen ones, I'll never feel the difference. It sounds like you got a great bike at a really good price. I don't think the difference is that much. If and when you go to sell it you can explain all this to the new buyer and they can see the upgraded components.