John, not that I have a lot experience with this (= kallitypes - I'm a print out process guy, when it comes to iron sensitizers...), but to my knowing, acidic developer (or fist rinse bath) does promote the oxidizing nature of silver nitrate and cause image degradation / bleeding - while the unexposed sensitizer leech out the paper. That's exactly why Mike Ware designed a new process, Argyrotype which doesn't use silver nitrate - but silver sulfamate instead. See
here:
"...An Alternative Silver Salt
Without exception all the iron-silver processes to date have used the most commonly available soluble salt of the metal, namely silver nitrate. But nitrate is an oxidising anion, and tends to dissolve the colloidal image silver during wet processing, especially under acidic conditions. To minimise this loss of image the Kallitype process employs alkaline-buffered developers of high pH, e.g. Borax. Alas, these create a new problem, because they cause hydrolysis of the excess iron(III) in the sensitizer and the deposition of insoluble ferric hydroxide in the image, which ultimately causes it to fade. In principle the cure is simple: replace silver nitrate with a soluble salt of silver having a non-oxidising anion. There are a few such salts known to chemistry, but most of them, e.g. silver fluoride, have unacceptable properties or a level of toxicity that debar them from 'home chemistry'. There is, however, a little-known and relatively innocuous silver salt that does fit the bill: Silver Sulphamate, NH2SO3Ag. This cannot be bought, but is easily made in situ, as I describe below. It can be employed in an acidic sensitizer of pH 2 to 3, which will wash out of the paper cleanly, without hydrolysis of the excess ferric iron, and without any tendency to dissolve the colloidal silver image..."
Therefore, I don't believe an acidic (or too acidic) developer is a good idea. OTOH, an alkali developer also isn't a good idea - even worse. (See Mike Ware's words above...)
Regards,
Loris.