I have a question regarding this. Does this change virtually mean that there can be an unlimited number of revisions stored? If so, do you think it would be practical to keep the option and have Composr prune old revisions after it reaches that limit?

It will keep unlimited revisions now.

1000 10Kb revisions would still only be 10Mb, so I don't really see an issue here, except if the disk files are getting annoying. In which case the "Archive page/file revisions" cleanup tool will sweep those away for you.

Ah okay. Yeah disk files would get annoying especially for heavy FTP users like myself. Though it may only take 10MB, FTP clients usually limit the number of files transferred at a time... so having all those files would slow down the transfer.