If I have to pay, then why shouldn't I adopt a RFC 3161 or X9.95 timestamp service? Some jurisdictions recognize them as notary-equivalent certified timestamps.
To get this service for free, just print your document to PDF, grab the free Adobe Reader, go to settings, signatures, click "Configure timestamping", then add a TSA server like:
http://timestamp.comodoca.com/rfc3161
or
or one of many others that are available. Then click "Work with certificates" in the sidebar and then Timestamp document.
As long as you can convince a judge that these are neutral third parties (very easy to do and there is much precedent) this should be satisfactory.
Or you could timestamp into the block chain, but then be prepared to spend a lot of time explaining to a confused judge why it's valid.
The technology used by such an authority would be just as complicated and difficult to explain as the blockchain approach to timestamping. What you're counting on is that the judge would give more weight to legal representations made by an otherwise unverified "neutral" private entity than she would to a detailed explanation of the blockchain.
What is it that explains how the blockchain--which doesn't require trust--would loose out to a private entity simply because bitcoin tech is complicated, and because a representative of that time-stamping authority would be able to sit in court and say "trust us, we have no stake in the outcome of this decision"?
A lack of trust is supposed to be the primary benefit of the block chain, but it seems that in your view in this case it is more of a liability.
Ultimately it matters when there's a dispute over the integrity of the timestamp. Even if in theory a judge could verify a block chain timestamp for themselves, they won't ever do this, they'd just say "go find an expert witness you can both agree on" and then the judge would assume the neutrality of the expert witness based on their credentials. You always end up back at the neutral third party no matter what, whether it's a TSA or someone who is interpreting the block chain.
That's not to say block chains are useless for timestamping, far from it. But for the specific case of timestamping traditional documents in case of a civil legal dispute, you may as well use the fast, instant, widely used, well integrated and free option instead of paying a $10 fee to use Bitcoin.
The benefit of Bitstamped is the simplicity of uploading the file and getting a QR code to insert in a document so anyone reading it can scan it to satisfy themselves of the date it was created.
The file that gets Bitstamped could be anything - for example I could doodle my new algorithm on a napkin along with the words "designed by Me" and get it Bitstamped before I finish lunch, later, I add the QR code to my business plan (for example) to link the ideas therein with the napkin photo.