I've been using ImagePrint for years. The current version on my Mac Pro running Leopard is 7.0.
I'm printing to an Epson R2400 currently. IP using their profiles always produces more details in the shadow areas than when I print directly from Photoshop CS3 or Lightroom 1.4.1 using the stock Epson profiles. It does take an extra step the prints with a lot of shadow areas, it's worth it.
I printed comparison lately for Epson Enhanced Matte paper between IP with their profiles and the standard Epson profiles printing directly from PS. The differences are very subtle now as compared to a few years ago. In fact, if I didn't have the 2 prints to compare side-by-side, I would be perfectly happy with the results using the Epson profiles.
That said, I use Hahnemuhler matte papers a lot and the profiles from IP are excellent. If you print a lot to non-Epson brand papers, the excellent profiles for IP are worth the investment in the IP software. You can download just about any paper/ink combination profiles from Colorbyte Software's web site for free as an owner of the IP software.
I print mostly fine art images in very low quantities so the extra work flow step is not a big deal. If I was a high volume shop like a wedding or portrait photographer, it might not be worth it. Besides, IP is expensive software, particularly if you are using a Pro-series Epson printer.
Cheers.
Bud James
North Wales, PA