Thanks for the feedback, 8_octaves ... are you a Bösendorfer fan, by any chance? ... because I believe the Imperial does have the full 8 octaves? 
I've been living in Switzerland for over 30 years now (and four years in Hamburg before that), so I can read the Henle blog with no problem. Very interesting material! I would vote for the version with D-flat AND B-flat in the op. 14 nr. 2 sonata. When I look at these early editions, I get the impression that they were done with a lot more care than many modern editions today (Henle being the main exception, of course).
The question remaining in my mind is, why did they (1st edition) put any accidental in op. 10 Nr. 3 at all? If it were not there, nobody in his right mind would play B-flat, IMHO. Did Beethoven write that in his manuscript? I suppose we'll never know.
Hi Roberth!
No, I haven't ever played on a Bösendorfer, so I cannot say anything about them.

My username is slightly connected to a pseudonyme of my favourite composer! One only needs to subtract one from the eight!

...ok: hmm. To the sonata, and to your last sentence:
Yes, we perhaps won't ever know. Now, let's
imagine: He DID. And let's
imagine, that the first edition was exact.
Why the natural signs, then?
Hm. I looked at the
complete section from bar 133 to 176, and counted the Bs
: B-flats and B -sharps, and explicit B naturals appearing. As follows:
There are
143 B-flats to be played, ( onehundredfortythree !!! )
2 B-sharps ( bars 167 and 171 )
4 explicit B-naturals ( bar 146: 3 of them, and bar 162 one. )
So, nearly the whole section "circles" around the B-flat, as a note which is very important.
Now, if both Beethoven and the first edition HAD written the natural sign (the first editors must have had access to some manuscript, copy, or autograph-manuscript, but as we know, these sources are unavailable to us), then I could imagine, that they didn't do that only to
indicate that it's natural, now, (because that won't have been necessary),
but to indicate that it's REALLY (!!!) natural now, because in the brains of players, there are, until bar 177 begins,
143 B-flats and
2 B-sharps a piano player has played on the relative small room of 43 bars.
"It's REALLY natural now", they perhaps wanted to make clear: A strong
WARNING aspect being inherent in this natural sign.
( But that's only a vague idea I had, "pro" this sign. The "contra" side which I could imagine, I had mentioned above: Editors may be additors, which would mean that Beethoven would have postulated: "All piano players => good! They won't play a flat here, in spite of the 143 they have played before!", so he, if this was the case, didn't write the sign. - But the first editors may have thought a little different. )
But that, too, is only a vague idea I have.
More I don't know. Via analyzing what Beethoven did in other, similar, cases, could perhaps be interesting. But I don't know whether harmonic analyzing ( g major ? g minor ? how, what, chords, functions, etc. ) would be able to answer all questions here.
Very cordially, 8_octaves!