As a very broad outline I'd say there's a lot of overlap between some MCIM and some SI&T and it isn't unusual for people to move between. A lot of MCIM consultants seem to do some consulting and then do a lot of SI and a lot of SI&T people do a bit of consulting or have in fact moved there from MCIM. Possibly in MCIM you'd get away with being less technically inclined and more business focussed and possibly in SI&T you'd get away with having less client facing experience.
Of course in saying that there's a lot in MCIM who are pure 'businessy' consultants and their work would be very different to SI&T'ers at the more technical end of the spectrum.
I think MCIM are paid more as you're supposed to be more valuable if you're client facing, or something. There are variousposts in the forum about ACN salaries.
As for equally valued, dunno? I'm still relatively new to ACN but hope that helps and happy to be corrected!