newbie image questions

Hi Grasslist,
I just started using GRASS last week to do some image processing, and am hoping folks out there can answer some basic questions...

1) I have created a composite of three images, and want to export the resulting composite as a single band image. How can I do this? Is it by exporting as an 8bit TIFF instead of a 24bit TIFF?

2) Is there a difference between d.rgb and i.composite? I know the former outputs to a graphics monitor, is that the only difference?

3) Personally, I loved GRASS once I got it going. I am curious, how wide is the user base for GRASS? Why do some organizations lay out big bucks for ARC/INFO and other products when GRASS is available? GRASS seems as robust as any system I have used, am I mistaken?

Thanks for any and all pointers and tips...

Lars Bromley
Technical Specialist
American Association for the Advancement of Science
1200 New York Avenue, NW
Washington, DC 20005