I thought so too at first, but after playing my friend's refinery MET, it is radically different. While the ramps are in roughly the same place, everything else is different. MET, while a rush and challenging, is easy as pie compared to IM.
I think I give the slight edge to IM for gameplay and replay factor, but MET blows it away from a artwork, sound, rules and in general package.
I am a bit biased as I'm currently modding my IM with my favorite mixtape and music of all time and will soon print out a custom translite to match said music that will make purists' heads explode. It'll be fun to watch.
I feel MET is Borg's best game thus far, even if I personally prefer IM. If that makes sense.