Actually, this magnificent set is now available, superbly remastered with the latest advances. look for the complete sonatas and the five concertos on pristine records, located in the UK.
I applaud Backhaus for having the bravery to play the F# in the first movement 32nd note string. No, it wasn't possible on Beethoven's piano, but I think it can be inferred that he intended on it sounding that way. The transition back to the recapitulation was a bit unshaped (the two-note slurs), but I overall loved the 1st movement, despite (or because of?) the strange tempo choices at the end. The 2nd was brilliant, slow, but full of surprises and subtleties. 3rd was weakest, but enjoyable.