I have the reefkeeper 2, and from what I understand; the reefkeeper lite 1 is a very good unit. The cool thing is that it is expandable. You can add more modules, if you choose. With the reefkeeper 2, I cannot add anthing else (i.e. another pH probe).
I am very satisfied with the Reefkeeper 2, it does everything I want; but the new line of Reefkeepers are just better because they are expandable. The Reefkeepers are also easy to program and the tech support is decent.
Good luck with your purchase.