Well, from what understand, from what @oldnslow2 explained it, from entry level emonda to top it is as follows:

SLR>SL>ALR>S

If I am wrong, feel free to correct that. All model in each series use the same frame, but some have different forks and wheels.

Well @oldnslow2 is seems like DuoTrap is another feature, that I indeed would use. As I want to have speed, cadence data. And I would also add heart rate.