Thanks for these replies!
I went ahead and purchased the Trio and have had some good initial success configuring it to work with Hauptwerk. Configuring Hauptwerk to recognize the Trio keyboards and stops was straightforward. Figuring out the best approach to integrating the Trio's combination system with Hauptwerk isn't obvious and is taking some time.
I initially had a little difficulty finding a U.S. supplier for the Viscount. One U.S. Viscount rep I communicated with indicated that the Trio was available in the U.S. only as a complete set with bench, stand and 30-note pedalboard for $8,500. I already have a bench, stand, and pedalboard, and wanted only the keyboard unit. I might have considered the entire set if it came with a 32-note pedalboard because I currently have a 30-note pedalboard that I want to replace and have really missed those extra 2 notes for the literature I play. I learned that Viscount recently added a 32-note pedalboard to their product line, which is great for the U.S. market because there aren't many sources of midi pedalboards in the U.S. But the 32-note pedalboard reportedly won't be available in the U.S. until this fall, and apparently won't fit in the stand that comes with the Trio. So I knew I didn't want the whole set.
I ended up purchasing from Kraft music:
https://www.kraftmusic.com/viscount-can ... organ.htmlThey special ordered it for me and it arrived within two weeks.
I am really pleased with the feel of the keyboards. They are a nice upgrade from the M-Audio units I've been using with Hauptwerk for 12 years. I am also happy about having real stops and pistons to use instead of a touch screen. I like that I can sit down and use the Trio without Hauptwerk when I want to do a quick practice session. I've never had a dedicated computer for my Hauptwerk setup (can't justify the expense) and it's nice not to fiddle with hooking up the laptop every time I want to sit down and play. Finally, I want my children to be able to play the organ when I'm not around to set up the laptop, and now they can. I will say that the music rack is not great and is a LONG distance from the bench. I'm going to investigate solutions others have suggested.
I am enthusiastic about this new setup and hope to find time to write up some additional notes when I work through further integration with Hauptwerk.
Stephen