[hbens]

Arch,
After seeing your shroud I'm considering getting some exit ducting made. I haven't secured the outdoor unit to the floor yet so there is some room to move it a little. It is only bolted to the 2X4s right now.
Getting rid of heat on the outside unit and getting enough airflow through the cassettes are 2 key concepts I keep thinking about.
I've been working on this project since the end of March. I think it took me about 6 weekends to get it to the testing phase. I did a lot of thinking and redoing some things. Then redoing my redoing.

One thing I was surprised about is the ease of access to the floor from the basement. Pulling the insulation board from the basement ceiling exposed the subfloor where I could see exactly where the 2.5" Aquahot ducts enter under the cabinet. I could also eliminate a turn in the 4" elephant feet ducts.
I'll think about this a bunch and consult some gurus before I do anything big or irreversible.