My personal opinion would be to get the ‘climbing’ (non aero) bike. The difference in aerodynamics is far outweighed by the ability to swap out stems, make easy adjustments, and the overall ability to work on your bike. While the aero bike may technically be more aero, the other is technically stiffer and lighter. You can’t go wrong with either, but the Ultimate will give you less of a headache in the long run.