I didn't previously respond to your post because I have no knowledge or experience with the iX line. So I don't know whether they use the same drivers, etc. I do have one iQ12 and planning on getting a second one in a week or so. Robert, on the other hand has a number of the iQ speakers and really likes them. We were actually discussing the iQ line last night (waiting for the forum to go live again). One thing he mentioned that he noticed with the iQ is that you can push them hard without any noticeable distortion.
The one advantage of using the Ultranet interface is the ability to set some of the DSP settings in the digital console itself, such as the speaker emulation, etc. Unfortunately not all settings are currently available from the console. TurboSound does have a nice editor that can be run from a laptop and connected to the speaker's USB port.