(received privately, answering publically)

...

any AS owner who wants to localize these updates can do so by simply anycasting the 192.175.48/24 netblock and serving dns on .1,=20 .6, and .42.

Will it be a _bad_ thing if I just null-route those addresses in a controlled/documented/restorable manner in the ASes and other sub-AS networks that I administer?

not at all.

Will it break anything valuable to you or to end-users inside those ASes?

nope.

Is there is a certain reason I should run a real DNS server on 1, 6 and 42 (besides, of course, collecting statistics and chasing ab|users) ?

nope.

Is there a centralised place with information on the blackhole-X anycast addresses and AS112 or a document with the proposal and implementation besides www.root-servers.org ?

um, nope. if you think it should say more than it does, let us know and we'll plump it up.