The more advanced printers also vary droplet size <4 pico litre, and will show even more difference (paper quality also makes a difference). Also don't forget that the human eye (or rather the brain) can resolve much more detail than the sample would suggest. The phenomenon is called "Vernier acuity". Besides, sharpening the output at native printer resolution gives cleaner results than sharpening with larger radii.
I wasn't familiar with vernier acuity even though I have used it many times when taking readings from instruments. A quick google search shows a couple of interesting articles: here
. The essential points are that vernier acuity can be as high as 4-5 arcseconds rather than the commonly reported value of one arcminute, but that this type of acuity is contrast dependent. I'm not certain how this type of acuity would apply to most photographs which do not have high contrast line patterns.
Human vision is astounding in that it uses a relatively crude sensor (the eye) and then processes the information in the neural pathways and brain to achieve very good perceived results. If only we could to this with our cameras!
Although the eye can resolve down to one arcminute (giving a resolution of 30 cycles per degree), the contrast function peaks at about 6 cycles per degree and this is the basis for SQF (subjective quality factor) as explained by Bob Atkins
in an essay for the intelligent lay person. MTF in this range is most important for the perceived quality of a print and this value is considerably below the limits of visual resolution.
Although most photographers want their images to be as sharp as possible, most observers would not view an 16 by 24 inch print at nose tip distances and good results can be obtained with resolution that is lower than the limits of visual acuity, since the eye is most sensitive to 6 cycles per degree.
Theoretical considerations aside, I think that the suggestions of Bruce Fraser and Jeff Schewe as outlined in the Real World Sharpening are reasonable for practical photography of most scenes and that is what I use in my own work. Most of the time we do not have as much resolution as we would like, but as the megapixel count of cameras increase, downsizing is necessary either in one's editing software or in the printer driver. As per recent discussions on this site, we probably should give more attention to aliasing and down sampling our sharpening halos out of existence in the process. Also, more attention should be given to image restoration algorithms that go beyond the early 20th century unsharp mask.
I would value your opinion in these matters.