This is how it should work IMHO
My only concerns would be that I do not believe any form of "digital" copyright has been tested in the courts yet so there has not been a legal ruling relating to digital formats of registering copyrights, therefore no precedent has yet been set as to whether digital formats of registering copyright via the internet are legally acceptable.
Could it be proved 100% that a digital file could not be altered or amended?
This could be argued either way - which is why a legal precedent would give a "once and for all" ruling
The legal system is always playing "catch up" with technology and I do not see this situation changing any time soon!
The other concern is whether companies like this are reliable - ie are they going to be around in 10 years time if/when you need them? Are they as "secure" as they claim?
However, if it is free then there is little to lose and I can see it being another piece of proof that you wrote a particular song at a particular time
If you are worried about copyright then I would use this "as well as" other means rather than instead of
