They don't really "blend" in the sense of a normal tweeter, because the output from these is almost entirely too high to hear. They use a switch with 5 levels. The first two are I think 4dB increments, the top three are 2dB. Something like that.
So you don't hear it as a tweeter, and none of the normal effects one would expect actually happen. Imaging, for example. Normally one would expect it to be ruined by adding a tweeter so far apart. If the output was in the tweeter band it almost certainly would. But in this case the output is so high it is not heard as a discrete source, not heard at all even, and so imaging actually improves.
There is a point where if I turn them up too much certain things take on a harsh character. Cymbals go from ringing and sizzling to grating. There's a sense of more air and presence but also this harsh edge. Moabs at 98dB are pretty sensitive speakers, but Townshend makes them to go with horns, some horns can go to 104dB, so it makes sense the Level 3 mine are at is about right.
Even though they don't blend in terms of tone, there is still some work to do getting them down closer to tweeter level where they will probably integrate better. Hard to imagine the imaging getting even better, but we will see!
