As for as using MC for IG installations, you can order MC cable with both a solid green conductor and a green/yellow stripe conductor. It's not really cost effective to use that cable. You might as well use conduit. MC comes in about any configuration you want. I believe you can get it in large feeder sizes as well. I am bidding a job that calls for weatherproof (pvc jacketed) #8 MC to run on the bottom of sewage treatment ponds to aereator motors!