I know ImagePrint pretty well, since I used it since 2003 on all our LF Epson (no 5, Ep11880 & no 6, Ep9900 now).
And I have to split your request in some parts:
Pros:
1. It depends in what you use the printer for and how much.
For small-singel-images-RGB workflow, you'll get out the same quality with the driver.
But, huge files, a load of images at the same time with different sizes, finetuning colormanagement,
all at one printingpage; then IP is unbeatable.
2. ColorBytes database with more than 27.000 profiles, for free.
2. Inklaydown is more effective than the driver, as much as 25% lower.
3. B&W with IP's unique gray-profiles, and with very subtle tinting of the image.
4. Slightly better shadows and highlights due to another type of screening.
Cons:
1. Cost
2. Another software to learn.
3. Gamut and D-max not any different than with a proper profile and the driver.
Probably some LL-members will give you the advice to not use a RIP, but for sure, when it comes to a big workflow, then IP is a workinghorse.
/Sven