PlotVitalNPC

So screwing around in sandbox mode, I've had a good time with the SURGE engine/reactor - flying around on Kerbin for awhile, then deciding that instead of beefing up my intakes I'm gonna get into the stratosphere by screwing around with an alcubierre drive, then ultimately ditching the craft far from any planets in the kerbol system to prevent kessler syndrome after realizing I had no way to deorbit it. It's a nice, reliable engine as long as you have an atmosphere to stand in for the remass you definitely aren't carrying enough of, and a worthy powerplant if you don't. What confuses me more is the SAGE engine - what sort of humungous machine are you meant to install that on, to get even the slightest utility out of its absurd pushing power without overgeeing your antimatter storage (especially since you need two of them in order to guarantee symmetry, since it doesn't snap to nodes at all)? Plus, you know, the whole thing to do with how it's an antimatter powered jet engine, an inherently scary concept.

Is the Muon Catalyzed Fusion reactor suitable for thermal engines?

Looking into that reaction chain, it seems like an interesting one. I can definitely see how it would be more viable than bashing protium together as a direct energy producer. What about the reactionless drives, though? I know I've seen them both mentioned in this thread, but I can't find anything that indicates what would make one preferable to another.

Are the Mach Effect drive and the EM drive specialized for different tasks? Is one an upgrade over the other? Or are they just kind of redundant with each-other? Also, I saw an image of muon catalyzed fusion in this thread, running proton-proton-proton fusion and making 50mw fully upgraded. That seemed weird to me, because from what I gather it's a fairly advanced fusion type, and I've seen other reactors making far more power at that size, but is it just because of the fuel mode? I've seen from the table at the start of the thread that proton-proton is a pretty wimpy fuel mode in terms of power output rate. Is PPP similar?