Historically, Roger appears to have been interested in systems with at least a vague resemblance to Bitcoin:
While I haven't used stylometry software or other means to try to confirm this, Roger's blog posts and e-mails for the Tor Project seem to bear some stylistic resemblance to Satoshi Nakamoto's e-mails as well.
Has anyone else suspected this?
Others may completely disagree, and this is purely a speculative hunch on my part. It goes without saying that I would be delighted if Roger considered answering this question directly, since I have the utmost trust in his honesty and integrity. Cheers!