@Porkloin I just finished up a set of Sony/Coral Holey baskets driver in a Nagaoka style double horn. This is my first real attempt at a full range driver, and I was shocked at the results. The Holey basket is around 4" diameter, so similar to the driver you mentioned. My first observation, the highs are really good. In the week or so I've been listening to them, have not wanted more highs. Midrange is killer! I mean it's shocking how good the midrange is, and I was expecting it to be great. Bass is good for the speaker size. I can't see these even being an option for me, without the double horn. By ear, I'd say these are getting below 100hz easy, with an in room F3 around 75hz maybe. If you listen to Metallica, this speaker is not for you. If you listen to Sonny Rollins, this is certainly the speaker for you. I have added 2 small subs crossed over at 75hz, and I'm very happy with the blend so far. It might be the best I've heard Linda Ronstadt sound on my system.
If you go for it, build the right box. Back loaded horns are not an easy build, but well worth it. I documented my process, and hope to have a build video done soon, to share. With the right system, and the right music tastes, I see why folks love these so much.