It is a major setback not including every feature from Scissors into WP core functionality as of version 2.9.
Especially the option to limit original image size is missing, which comes handy for a number of reasons; e.g. band width, collaboration with Lightbox 2, no need for downsizing every high resolution image, storage capacity, just to mention a few.
After searching the web there seems to be that the above is the overall consensus.
I hereby urge you to integrate Scissors full functionality into WordPress core as quickly as possible. I'm certain that standing ovations would emerge from an unified WP community.
Good luck - Best regards