Varifocus

I have been researching the purchase of a new micro four thirds camera.  I was thinking of the Panasonic GH4 or the Olympus EM1 but I am not convinced they will improve greatly on my G3 so I might go for a macro lens instead.  I have considered a full frame Nikon or Canon but am put off by the weight and the need to buy new lenses. Any suggestions will be gratefully received.  I tried experimenting with my long lens and narrow depth of field on my walk out today.