Gyroscope Part

@AnotherFireFox I think you have a typo in @AndrewGarrison, but he marked it fixed in 0.7.1.3 anyway.

Shouldn't you mark it "completed" @AdnrewGarrison

CMG (control moment gyroscope)

just read my motto on simple planes!

So long as it's not so powerful as to completely replace RCS. Things like slow, but precise adjustment for large craft seem fine, but additional reaction wheels or control-moment gyroscopes making the reaction-control system useless for actually controlling anything seems a bit counterproductive.
Mostly for the sake of realism, but also because personally I like the design challenge of building RCS-friendly craft - even though in its current stage the game isn't exactly RCS-friendly itself, but that's for another suggestion.

I think it’s best use would be for full-electric control of a small satellite. At the moment, we need RCS to control tiny satellites so it would be handy to have reaction wheels/gyroscope that act the same as the command module. @AndrewGarrison

I will go out on a limb and say torque wheels. I think torque wheels are more realistic depiction as they can greatly affect the orientation of a craft. From what I know, gyroscopes are those spinning bois that we topple just for it to not fall.
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But yes that should be implemented nonetheless

@AndrewGarrison yes

@AndrewGarrison I think he means like ksp so you Can put another sas module on a craft maybe because it to big maybe.

Do you mean an additional gyroscope part that you can attach anywhere on your craft to help improve its attitude control?