@Kubla Cant -- Re: 2560 x 1600 - About Time.
You're correct of course, visual hinting always applies to font size. It's the stuff that has to be tweaked because of the limits that pixelation imposes to which I was referring.
You're also correct about the granular phenomenon and the rough paper of the period. Nevertheless, even then paper varied very considerably and some of it was remarkably good--much better than today's paperbacks for instance. Also, printing from that period onto non-paper surfaces such as vellum shows how remarkably good these artisans and craftsmen really were--the fact that we're still using their fonts, Garamond for instance, with little change a half millennium later attests to this.
I've seen some examples of good 15th C. printing firsthand and up close and to say that I was impressed is a large understatement (mind you, as with today, much of it was also rough and ready).
Another aspect of old printing is that it was invariably letterpress, and one remarkable aspect of good letterpress (where inking is carefully controlled etc.) is that the impression caused by the type actually enhances the resolution. This happens when the ink pools at the edges of the type and in its serifs. The pooling has a similar effect to that of overshoot correction on a video transient or of unsharp mask sharpening in photo editing, it causes a considerable degree of apparent/optical sharpening to be achieved.
One thing that never ceases to amaze me is how remarkably good the quality of 19th C. books actually was, especially those from about 1850s onwards through to about WWI. Sure, there were lots of el-cheapo books too but those that contained drawings and diagrams and which were printed onto high quality paper were remarkably good. Even today, one rarely sees a modern book that has printing that's so acutely sharp not to mention the clarity of the layout style. Back then, printing was a profession of which whose members were obviously and justifiably proud.
BTW, if you're interested in fonts and typography and you're ever in Antwerp then I'd highly recommend a visit to the Plantin-Moretus museum: http://www.museumplantinmoretus.be/Museum_PlantinMoretus_EN/PlantinMoretus_EN.html