Klipsch Heresy IV

The cabinet size is obviously important when a speaker is ported, as you're just not going to simply stick a port in there without considering everything...including what the "new" 12" bass driver's design might be. Roy Delgado did a great job with the other new "Heritage" re-designs and it's reasonable to assume a lot of time was spent considering how to get another 10db of bass from the Heresy IV as the lack of low bass is a common criticism of them. Duke's or anyone else's opinion isn't as valid as what the individual listener thinks of the sound of the IV with the complete redesign, and thus ends my statement of the obvious.

10 db of bass ?....= 10 hz of bass. Guys ( and gals ). You need to look at some of the pro versions of the Heresy’s..........again, nothing new with the ported design, except for the port itself. R.D. had much to do with the design of the pro models. Amazingly, what needs to be done to the news ones, as well, is a " heavy layer " of Dynamat on all of these horn drivers. Danny Richie, on the mods of the Forte IIIs, did not do justice to the mid horns. A recent Steve G. video, about a fellow modding a Cambridge CXC transport, stated, that with every mod that he did, the Dynamat made the most significant difference, in SQ. Again, I’ve been using Dynamat ( and some roofing repair tape found at Lowes and THD ), for the longest time, on not only horns, speaker frames and cabinets, but on electronics, of every kind. This fellow, also recommends, to put a book on top of the chassis, something I have been advocating, for the longest time. I know, this mod stuff belongs on another thread, but I am bringing it up here, because it is a cheap, but very relevant upgrade. I know of only one person, who applied Dynamat to his horns, who did not find it superior in sq, and I do not, for the life of me, understand why. Enjoy ! MrD.

I have heard a few of Duke's speakers. They sound great. They also had rear ports.

I think it is patently absurd to assume that any redesign will automatically sound better than its predecessor. 

My point was and is that ports require a smaller cabinet than sealed. Last time I looked simple laws of physics applied to all speaker companies even Klipsch. 

I agree.  Until someone actually listens to the new Heresy, there's no way to tell.