noone1:

How does a convertible undermine ALA? It still works fine as far as I can tell. ALA involves the front end and the airflow through the wing. It might not be as effective with the top down due to the overall worse aero, but the ALA will still function.

Besides, the best selling version of the Performante will be the Spyder, just like everyone dumped their SV coupe for the SV Roadster. Given the negligible difference in real world usage/performance, people want convertibles more than coupes.

ALA functions as you have stated on the front of the car, controlling airflow under the vehicle and through the diffuser.  This, as you have stated, is not affected by the spyder version of the car.  However, with the wing and its blown airfoil sections, the air flow is sufficiently disturbed from the shorter convertible, when closed, and from the turbulent airflow, when open, over the windscreen header, that there should be concerns about its efficacy.  The coupé version has ram air intakes before the wing and directly behind the backlight.  Airflow over the backlight will remain laminar over that section of the car; the same is not true with the convertible as the airflow becomes detached and unstable with numerous vortices being shed.  At normal speeds, such as those found in the U.S. the lost efficiency isn't significant, but, it will become significant on the racetrack-do realize that few of these cars will ever spend time on the track-and its downforce vectoring system is hampered as well.