Do rolls beneath the base of CAS always gets them excited.
Actually vertical climbing manoeuvres will get TCAS excited as it is projecting the vector, over 5,000 fpm in most aerobatic types.
On a related topic, which may interest some, if you have an Avidyne TAS6xx box and your Mode S transponder fails, or gets turned off, the TAS still works. This is not surprising if you know how the system is wired…
