The Ripple knob does fit the Q1! Note that because it is wider than the stock knob, it rests on top of the case, this means that the click to mute functionality doesn't work.
The encoder doesn't fit fully into the insert of the knob, but it's definitely on there, and the fit feels pretty good.
Can't say definitely right now, but I imagine it would fit the same as the Q1. It should fit, but because the knob sits on the edge of the keyboard the click functionality no longer works. I posted pictures in a reply above.
Not out of the box, the Megalodon macropads don't use a D stem style encoder. You might be able to modify the plastic insert of the knob and carve it out to fit the round stem, but I haven't tried it.