There are only two systems - TMCC and Legacy. Legacy was referred to as TMCC II when it came out as it is the successor for the original TMCC system. It someone lists an engine as TMCC II, its a legacy engine.
The legacy system will run TMCC engines better because it uses absolute speed steps to control the engines. The CAB1 used relative speed steps. TMCC engines support both features but the CAB1 never took advantage of the other speed steps.
In regards to quilling whistles and horns, that is an engine dependent feature. Not all early Legacy engines have that feature. Odyssey II is more refined speed control over the original Odyssey system. You will have finer control over the engine and it will run even smoother. Some original Odyssey I engines would tend to jerk at very low speeds which forced the user to bump the speed up one or two speed steps to smooth it out. You won't see any problems like that with Odyssey II.
