I've seen and heard both exhausts but only travelled with the Miltek.
Miltek sounds more muscular at low revs.
Drone, none really, just a very faint hum at around 2k rpm which one can only hear if not talking, listening for it or radio not on.
It absolutely sings at high revs
I don't like the way the Eisenmann does not come with full pipes and one has to cut the OEM exhaust off!
Quality, no difference on the outside but personally the Miltek tailpipes look better and just seem to be a better visual match.