depends on how are you approaching this question. from IQ you might loose out a bit , especially with DoF **** I think is overrated anyway.
what you gain is - portability which is - well, obvious when you compare the two. the x100 might be more useable beyond iso800 too I think. at least the new small camera systems are better there then the old pro/semi pro dslr's .
om-d m5 - looks like it's going to be a killer ! I'm so looking forward first real test and nice price drops
actually om-d might be the only camera you'll ever need unless for sports etc.