objectively; the M9 can stay with an all analog signal path, and expected advantage in bass integration and extension. likely more authoritative sounding and might scale better with big complicated music. likely better resale advantages as it can fit into most systems as it is.
Ultimates would be expected to be more immediate and micro-dynamic sounding and disappear better. very flexible amplifier choices, but you need four or five channels per speaker. there is an all analog crossover option for the Ultimates, but it's not the highest performing approach.
otherwise matters of taste, both visual and presentation. and both are likely neutral tonally, so season to taste with amp and set-up choices.
Mike, what is this based on? Yours is the only cone SS system I have heard that scales more than horns. Henk's grands scale, but they are also a one off and not cones. Others are like 20 percent or less. They suffer at scale, dynamic range, tone, immediacy, coherence, bass, midbass, highs, and transparency. Every front, compared to the good horns.
Not saying anything in favor of ultimates vs M9 per se as I haven't heard either, the ultimate only at Munich (jazzhead heard it in the middle east he wasn't impressed).
Horns don't only excel at immediacy. And yes I haven't heard a DSP horn I like, but they can be made to scale as you please, like the ESD acoustics horn in Munich last year.
This is why I had unsubscribed from this thread, the discussion is pure masturbation