A good drummer is more important that it seems... it does not only keep the beat, but does a lot of very important things for the song, like remarks here and there. A drummer makes a song slow or fast, boring or interesting.
Richard plays a lot of types of guitars and he's very good but in my opinion is the one that can be easily replaced by someone else like, let's say, Robbie McIntosh. I won't miss the bouzoki or the rest of little things with strings on it at all.
Glenn is really a great bass player but I think he sometimes plays too much. I remember that Tony Levin said in an interview that a good bass player would be someone you don't notice is playing at all, that plays very little but when plays does exactly what the song needs. Glenn plays too much and his playing is all over the song and over others instruments.
Jim is just fantastic. And Guy is very good playing soundscapes, probably there are many many other synths player that can do what he does and probably someone would do it even better, but it suits MK needs musically talking so, heads up.
Ian is a good drummer, that not only keeps the beat but also adds remarks wherever they are needed. he's not too noisy as Chad used to be, and not that fast, sometimes too fast as Terry used to be. Anyway, I would say that Danny Cummings was the best drummer MK had, but I rather have him on percussion so, let's add Ian as the best possible alternative.
The folkies are just fantastic, and the brass section... Tom is very good and Graeme did something very interesting... nobody is missing Nigel Hitchcock so I bet that's because of the great work Graeme Blevins is doing.
I agree that adding Paul Franklin on pedal steel would make it just perfect.