I found out something interesting, the 2200 at least will reregister a sheet for a second pass with great accuracy if you set the guides tight against the sheet at the outset. I was playing with a scan from a 4x5 and output it to some enhanced matte paper, which is pretty dull stuff. I decided to play with it when the mediocre print came out and cut the highlights and most midtones out with levels and ran it through again. The result were encouraging enough to try a third pass with only the blackest shadows left after a levels adjustment. Though the print didn't show stupendous shadow detail when I held it up to the light the tonal range was quite good with lots of detail into the shadows. This tells me that a second pass on transparency should give you any amount of density you want with a little research and experimentation, and the 1280 may be able to do quite a bit better if it can hold the reregisteration.
Originally Posted by sanking
I tried it on some luster paper and found by the third pass the ink had sealed in the paper enough to give some problems in the darkest areas with ink absorbtion and left a little dull patch there.
It'll be interesting to see what happens when I get some transparent media to play with.