I am far from an expert. But as a M100 owner and a prolific researcher before purchase, It sounds like your preference would lean towards M100.   Momentum is from what i understand fairly flat EQ with accurate reproduction while the M100 is Modeofile which is meant to be fun but accurate...

Just got my white m100s. Have not had a real chance to listen to them yet. Here is a bit of order info for those waiting.   Recieved Tuesday 11th Sydney, Australia Ordered Oct 18th $40 shipping