Thanks. Yes these have been on the edge of my consciousness for some time. Recently they drilled right in.
I was musing about the DC1602SB around the time that I was picking your brains on all things Piano Forte. (Thank you.) Since then I have read everything that I can find on here and on the web. A number of people prefer the IX for reasons that make sense to me. Also as I scrubbed the web for pictures of the three models, I discovered that there are more reviews, blogs and vanity pages for the IX than for the X-CC and and VIII combined - several times more. Also on Price Japan, no one had requested a quotation for the other two, only the IX. The sample is statistically miniscule but it seems clear that the IX is by far the most popular IEM in the expensive PF VIII-X line. Why?
There was a moment when it gelled in my mind. Final Audio works primarily with stainless steel at the high end. Their (apocryphal?) $500,000 speaker bank, the Muramasa, the Fi-BA-SS all use it because it is rigid. That allows for the cleanest reproduction within the design parameters. My primary interest in the Piano Forte is the combination of open air, dynamic driver and especially the acoustic modelling. So as my first (and maybe only) PF, I want the rigid clean version. It strikes me as purest to the concept.
There is my short version mash of logic, inference and unreliable statistics. The even shorter version is that I suddenly really really wanted the Piano Forte IX so I bought it!
Delighted to be joining the club. I will let you all know what I think.