I am trying to understand better a few things.
1. When I see in magazines and online - large main studio speakers like the Augspurgers, and JBL M2's, have tweeters with horn/compression drivers.
2. But most studio speakers for nearfield, and midfield, for example, those reviewed in Sound on Sound, use dome or Ribbon tweeters.
Which is better, compression driver/horn tweeters or dome tweeters?
Are cost savings a reason why dome tweeters are the de-facto standard in nearfield/midfield speakers.
Why are compression driver/horn tweeters not used in most nearfield/midfield studio speakers?
..better (in this context) is a subjective quality, assuming similar objective results - it's really up to you what is "better". I tend to favor (treble) in-order: Ribbons, Heil/AMT, Electrostat, Planar, (good domes), compression drivers. So between a good dome vs. good compression driver (ALL ELSE EQUAL), I prefer the dome tweeter. As you move into the midrange, my preference changes, there I prefer Electrostat's and specifically in a dipole radiator.
Dome's are often less expensive than compression drivers - at least on an OEM basis and when comparing a typical 1" dome tweeter to a typical 1" exit compression driver. To consumers though there is large range of choices/prices.
In a near-field basis (less than a meter distance from the monitor), the integration window (polar/directivity response/summation between the drivers) for the tweeter + midrange/midbass becomes more difficult for a horn loaded tweeter, be it a compression driver or a dome tweeter, within a short distance (..depending on the *size/depth of the horn and diffraction artifacts). The subjective result is a "disconnect" between the tweeter and the midrange/midbass - with a typical "I can hear the tweeter" effect.
*small (6" or less) round shallow depth waveguides/horns often integrate reasonably well at shorter distances, and can even help with dispersion matching between the two drivers.