Mark Dubovoy's interesting article condemned me to more than a weeks worth of tests comparing IP and Epson prints.
For this evaluation I'm using IP6.1 with Ilford GFS on my R2400. Having spoken to Colorbyte support I understand that the print engine for 6.1 on the R2400 is the same as that for IP 8. Indeed they advised me that, from a purely colour management perspective, there would be no advantage upgrading to IP8 (for an R2400).
On the Epson side I'm using a custom made profile (i1 iSIS D50 with UV cut) with LR3.2 on a PC. With IP - the RF3 profile on the lossless tif image exported from LR. Both with perceptual intents.
Here are my observations.
I agree with with Andrew. IP gives me a magenta shift in some blues. In extreme cases it can be quite severe and prone to microbanding.
I agree with BradFunhouser. I prefer the skin tones IP produces. I find all Epson profiles ever so slightly yellow - clearly visible in skin tones.
I agree with much of what Mark Dubovoy says, particularly about the "slightly purer whites". But I very much disagree with him about IP's coarser dithering - I much prefer Epson's rendering - perhaps if I my prints were bigger, IP's dots wouldn't be so visible. Mark says "more accurate blue tones". I would say different blues sometimes blacker, particularly on Baryta papers, and sometimes more magenta.
With the Epson driver, one strength of my custom profile v the generic profile is that it improves shadow detail markedly. Even so IP gives me still slightly better shadow detail. This is only with perceptual intent. For me, with this paper, printing with IP using a relative intent destroys shadow detail and greatly reduces Dmax. When printing With a relative intent even the generic Ilford profile give much better Dmax and shadow detail than IP.
With the advent of IP7 Colorbyte produced a completely new set of profiles called DCM. For colour work I believe these are backwardly compatible with previous versions - it is only in monochrome work that the DCM modifications are embedded in their software and require an upgrade. In my experience the DCM profiles give yet more shadow detail. But, at this level, I am not sure this is always desireable or could not be achieved through manipulation in LR.
On another thread about Mark Dubovoy's article Eleanor Brown says she is now "getting stunning results from my epson drivers on both my 7900 and 9880 printers provided my files are properly prepared". This, I think, is the clue. Epson printing technolgy and profiling tools are continuously improving. I may be wrong but I feel that the recent updates for IP have been more layout driven than colour management driven and, unless IP ups the ante, the one will overtake the other. Perhaps, as BradFundhouser asks, maybe this point will arrive with X-Rite's new profiling offer. Unless, as I suspect, it has already happened.
From a print quality perspective only, is it worth the money? If Colorbyte offered me a full refund I would probably not accept it. But I hope and suspect I will not have to buy an upgrade for my next printer. Or, who knows, perhaps I will. It can produce great images. However, even though I own IP, I usually stick to LR and the Epson drivers.
And please forgive me if my R2400 is so now old hat that none of my comments are relevant.
Hope this helps,
"Joe User" (Peter).