Map,
ERR and HR-1's are both similar to Ohm CLS. Actually, Steve's (the owner) write-ups of the development of the ERR suggest that the Hegeman Model 1 and Ohm Walsh speakers were his inspiration.
The Decwares don't have any rear attenuation. John S @ Ohm suggested to me that this would cause some more trouble placing the speakers, and also maintaining the image throughout the listening area. I mostly listened to ERRs nearfield, and was having a little too much fun to remember to test that theory. The main radial driver in each Decware runs w/o crossover, with a single cap limiting tweeter. The cap can be changed, giving you some tweakability (Decware definitely has a tube-centered, tweaky philosophy). Tweeter is directional, and I think blended in somewhere around 6k (radial driver has natural roll-off at about that spot, apparently). Nice, deep, taut bass is driven by the radial driver loading a passive radiator at the bottom. Can run on 8-ish tube watts, but they were too limited for me there (and Decware will tell you that too), so they really need a good 25 watts at least.
So the ERRs and Ohms are almost identical (other than rear attenuation) in philosophy. ERRs are more efficient, a little more refined, smaller, and physically more delicate. The fit and finish surpasses both my 2000s and my Center channel microwalsh. Duevel, German Physiks, most MBL, Omnisphere, Morrison, Huff (if he's still in business), HHR... they all splash treble around the room, and use some conventional pistonic drivers, whereas Ohm, Decware, and Parallel Audio have directional delivery for high frequencies, and omni-directional delivery for everything else.
As far as bending wave action (sound propagating sideways off the driver, instead of coming off the face of the driver), all pistonic drivers do this, but in most designs it's to be avoided (contrary to Lincoln Walsh's design philosophy), and to what extent the current Ohm CLS driver and Decware radial drivers truly use this principal I couldn't tell you. I did flat out ask John if they still use that transmission line principal and he assured me they're still designed in this fashion. I have absolutely no reason to doubt him, he more often has talked me out of a purchase than he has tried to talk me into one (which has never happened).
The HR-1s add a midrange driver forward facing (and a little schnazzier cabinet). I believe it also uses 6" radial instead of 8" on the ERR. That midrange driver does have a passive crossover in front of it, which is somewhat of a departure for Decware. That was apparently quite a nut to crack (10 years??) to get it to blend. Wow was it worth it. Musical, deep, very quick, silky smooth, and (best of all) completely engaging.