I have Imageprint Lite with my 2400. Among other things it gives you the advantage of very good profiles for just about every paper there is and I think this is part of what you are paying for.
Essentially, for colour images, I think you want the printing application to produce very neutral images. As has David Good suggests, I use my editor for making colour adjustments and then trust the printing application to reproduce the result as faithfully (neutrally) as possible.
For all the papers I use I now find Imageprint profiles and custom made icc profiles both produce remarkably similar results. Both are excellent but there are some very minor differences.
To my eye these differences are.
1. Imageprint gives slightly better shadow detail.
2. In some instances Imageprint has a slightly more visible dither pattern and, with my setup, on rare occasions can exhibit some microbanding. Colorbite commented that this microbanding could be overcome by changing the media settings.
3. I think Imageprint is marginally more neutral than my Custom icc profiles. Or perhaps I should say that I prefer the Imageprint profile - to me Imageprint seems very slightly less yellow which I like but it is a very close call. Generally I use Epson Exhibition Fibre and Ilford Gold Fibre Silk.
Having said all that I now rarely use Imageprint and find that Lightroom (version 2 onwards) produces images I am more than happy with.
I have not done any serious Black and White work so I can't comment on that field.
Hope this helps,
Peter
