The Soft-Lite and OKNA are very nice double-hungs. If I HAD to have a hung window because of architectural style they would be on my list. That being said:
1. I don't like single strength glass. A projected window (casement or Tilt & Turn) can take three panes of double strength glass. I'd really blike to see some hung windows set up for 1 1/8 IG units. You'd get great performance with only argon, and have room for three nice pieces of 3mm glass.
2. The projected window can get nearly the same glass performance with argon as krypton, because there is room for two 1/2 inch spaces. As diffusion occurs, the argon units will lose less performance.
3. The smaller spaces and single strength glass of the hung windows makes it more likely glass will kiss on extreme cold days. Triple pane reduces, but does not remove, this threat.
4. I don't like normal foam-filling. It is often just a cheaper alternative to multiple chambers. Yes, it might give a tiny little bit better insulation than a well designed multi-chamber unit, but you run the risk of weld contamination. (If you ever look at how Passivhaus windows (super high performance windows for passive solar houses) are made out of glass fiber reinforced PVC foam inserts are put in after cutting and cut short of the ends of the extrusions. Germans are paranoid about weld contamination
5. Units might test at 0.01 now for air infiltration (The newer weatherstrips really are getting better.), but will not hold performance like a dual or triple compression seal. Also, the test is at 25 mph. If you ever witness a double hung in a structural/air infiltration test, you'd see how the sashes start to bow at higher wind speeds. The tilt-in design with just corner supports is just to flexy, even in a structurally sound window. Air infiltration goes up much faster than linearly with wind speed as a result. Overpressure closes a casement sash tighter, and the Tilt & Turns have full-perimeter locking (if they are good) and such heavy extrusions that sash flex is nonexistent. (At Fensterbau this year I saw a waterproof window made this way, as in waterproof for for flood protection, not rain protection
The short version of my opinion: high performance double hungs for replacement where you need them for style, high performance projected windows everywhere else.