it always depends on what people know...
I work on Linux and Windows in parallel, depending on what happens to be better suited for the actual task. You do, too (sometimes), right? When developing code, I HAVE to use both OSs (to check my code). I don't own a MAC though.
People being in commercial computing (like Wilfried) might also be "multi lingual", who knows
I know that Wilfried and colleagues are using also OS-X besides Win 7, and ISIS 3 has some (limited?) support of OS-X.
My experiences with GDAL were quite bad in case of JPG2 'monster' file conversions. Under Linux it worked OK( but VERY slowly), but under Win 7/64bit it crashed regularly after some time. Same for a number of other users. As concerns myself, I am not using software giving me such experiences.
You probably use GDAL mostly under LINUX!? Did you recently try it under Win 7?? I think there is a bug in the GDAL memory management for 'monster' file challenges in Win 7.
PS: Since a few recent subversions the ISIS 3 installation is MUCH faster than it used to be. And it's completely automatic. You can go for a quick Thai dinner or a Sushi in the meantime