I saw the Aethos and was wondering the same. so what the deal with that bike vs the SL7?
The Tarmac is a race bike, where the Aethos is not all about aero but all about being lightweight. It is lighter than the UCI minimum weight.
Pretty good preview of it on cyclingnews.com, but I thought this part sums it up pretty well.
A big part of Specialized’s design process was for the Aethos to be uncompromised in real-world riding which means it must match it’s climbing prowess with descending capability. Geometry and handling has been lifted straight from Specialized’s dedicated race bike, the Tarmac SL7, and has so far been nothing but precise allowing pinpoint apex calculations through corners and beautiful weight distribution.
When the SL7 was launched earlier in the year, Josh described it as a 'weapon of race destruction' in his
Tarmac SL7 review, likening the SL7 to a lightweight Venge rather than a true descendent of the Tarmac line. With the new Aethos, Specialized may have found that lost Tarmac DNA and evolved it into a whole new species.