I personally don't see those two years as too long, I see it as a great opportunity to learn a new language (something that does not seem feasible in a 1 year program) and I think that summer between years would be a great opportunity for good internships (I have no experience in IB).
IC vs WBS: I only have the information I've gathered through hours of lurking in the forums, but the general perception is that Imperial and Warwick are at the same level in terms of placement and name and just below LBS, Oxbridge and LSE, but above all the rest.
I like that Warwick is not in London, so I don't get too distracted (and the life is cheaper), but Imperial seems to have a lot of potential and is growing very fast (I see Imperial articles and research papers referenced very often, and I am a big fan of their student's magazine, called Felix).
BTW, I will check the MAFINRISK to see it fits my objectives, although I don't see myself as a quant.