My fineprint is an unregistered copy 5.5 .. maybe it is a trial that keeps on ticking. I'm ready for a real registered copy when I know the advantages, the best discount, etc. since my trial or whatever it is has gone on for years and saved me tons of paper (the real help isn't the cost of the paper, it is the convenience of carrying around or filling less sheets).
On install attempt Greenprint did a few funny things, telling my firewall to call out to a place on avast.com (yes, the anti-virus company, I checked the url) many times, asking for Net 2.0 (which I think is installed already) .. so I haven't yet got around to trying it as the alternative.
(Yes, the Bits was yesterday, sometimes the company will honor it a day or two later, you just email them, explain the situation, and they try to set up a special purchase code.)
As for comparing the two (and any others) I have not found anything on the net. Fineprint is close to bulletproof, excellent. I also use their .pdffactory to convert purchases and such to .pdf to store in a special folder as a paperless office history.