i've just got one of these. can tell you right away that the construction is far better than the vestax. in the loop i don't think there is much degradation of the sound. i used it out for the first time last friday. if there was it was no where near as much as the vestax.
if you are used to the vestax isolator then you will get a little shock at the crossover frequency points. on the bass for instance where the vestax takes out a lot of lower mid as well, which can be a quite brutal cut (very effective!!!) so the dope real is a little more subtle, being that is really is only the sub bass that is eliminated, so can still hear some of the bass kick, where the vestax would have killed that. it's on a system and not in the house that u hear the dope real in full effect.
i suppose the dope real is emulating the sound you'd get from say a rla 3 way crossover where the bass from going to the subs, middle is full range and tops go to the tweeters. correct me if i'm wrong here!! so that the bass kill here wouldn't be as savage as the vestax.
unfortunately i don't know of any mixes that have been recorded with this.
u should keep an eye on francois' deep space site for any new mixes when the recording has been taken after the isolator.
i have no doubt that the dope real is going to be a real addition to our set up