A lot of times what I end updoing is I have to import footage, setup it up with the right color space, then if I do a key I have to flop back to the wrong color space to get colors to react correctly, and then flop back.
For example some times with a color space transform greens are off the charts and won't key or other effects won't work on top. Doing a flip and the flop back usually works.
But just haing a swap button between the input and output lut would be great.