Mark,

Regarding the modeled aircraft, you are probably correct: Whatever manuals they could get.

From a user standpoint the -177 has definite advantages…the altitude capture alone is nice. But you could also do some nice things with CMD position selected.

With appropriate paddle in CMD position:

 -By de-selecting the pitch mode, you now have CWS available, but with the protection of altitude capture and remaining in a lateral mode, if selected. This is a great feature when climbing, or descending. On some units LVL CHG would cause the pitch to chase the IAS, or be abrupt when selected.

 -When using heading/nav mode, you can also de-select giving CWS roll, while maintaining a desired vertical mode –LVL CHG; VS; ALT HOLD. This feature is particularly nice maneuvering around weather, or intercepting a localizer, for example.

The system was also much more adept with autothrottles than the -77. In fact, very few airplanes I ever saw had a/t when SP 77 equipped, but it was available.

“Flying” the -77 keeps you more honest. Once the -177 was incorporated, then it would a VLF next, or like some have requested, an FMC.

Sean