Yes--I've measured everything and listened carefully to the RHL CG4 ($250 per) and the NHT SuperZero 2.0 ($99 from Amazon). My goal was to see whether I could recommend either of them as inexpensive surrounds for use with my Philharmonic speakers. I'll just give a brief summary here, along with on-axis measurements, and measurements 45 degrees off axis. Measurements of the RHL in Home Theater magazines had shown a kind of funny depressed bass and upper midbass region, and then a ramping up from around 700 Hz on out. The question was whether my measurements would replicate that, and whether they really sound the way they measure. The short answser is Yes, and Yes. My unit measured pretty much like the plots you've already seen. The sound lacks some body, and the upper registers stick out in comparison. The sound is clean, and there's certainly no muddiness in the bass. Further, the off-axis measurements are excellent ingnoring the basic signature of the voicing. The drivers are high quality, and the tweeter appears to be a very nice and popular Vifa unit.
As the on-axis measurement shows, the little NHT is much better balanced. It sounds more cohesive than the RHL, and is basically neutral except for a little edginess in the lower treble, which also causes them to sound a little opaque compared with the RHL or a little monitor I designed as a kit some time ago (the MB0W1) and used as a reference in my listening. The tweeter is no match for the RHL unit in terms of ultimate extension or off-axis performance. That may also contribute to the slightly opaque sound. But they cost $99 each. You can't have everythig, and I think they would be a very decent choice as a cheap surround. The basic voicing is closer to the Philharmonics than is the RHL.
Could I recommend the RHL's? I guess. Maybe. Sort of. I doubt that the zingy voicing would be that much of a drawback on surround material, and they do have a very open sound. I'm keeping the one I bought and will revise the crossover when I get a chance. It has the potential to be a very nice little speaker. I have no idea why the company didn't build in more baffle step compensation to give them a fuller, more balanced sound. The crossover is fairly complex with good component quality. No tiny gauge inductors in the woofer circuit or electrolytic caps in the tweeter circuit.
