My pleasure to chip in. I spent a looooong time researching turbo tech for my upcoming 2.3L turbo build. In the end, I went with a Mitsubishi Evo IX TD05-16G with 10.5cm hotside for all of the reasons above. Of course I had Chad Block and Blouch modify it into custom 650 cfm, 400+ HP capable beast that hits 1 BAR @ 2500 RPM on a 2.3L motor and blows 1.5 BAR+ without boost taper to 8000 RPM.
I agree with you that Brian's headers are by far the best 911 Turbo header on the market. Once my short block is done, these will be purchased.
Yes, TTs are a great alternative if you can't twin scroll. I mapped TTs for my motor and the boost curves and transient response curves I extrapolated from existing data looked identical. Draw your own conclusions... smilewavy