Amazing ... the original files must be massive Graeme given the amount of detail you're capturing when you bring the various elements together! :)

I usually lose about 2GB of drive space for every one I do - I don't post up the full resolution ones as Google can't handle them (rejects images more than 12000 pixels wide - originals are at least 16-17,000 wide). The finished panorama file is usually about 680MB before I scale them down and convert them to jpeg :)

Storage and backup is a problem!