[]Omegatron said:
Redesign of every single template file at very least. [/]
Yes, I'm aware of the complexity---three years ago I redesigned the W3T GUI, which involved changing every single perl script.
There were no templates, so I had to sort through the code to find the HTML. It was a mentally draining project since you had to keep complete focus and finish a file when you started, otherwise you would almost undoubtedly be lost mentally when you went back.
I don't think a CSS conversion would be quite as hard in that sense, but might be harder in terms of designing a new interface that accomplishes the same things technically as the current one, without departing too much as to make users re-learn the basic navigation.