For what it's worth......
I use an Epson 1280. The system is the same, but some of the names change to protect the guilty!
I've been using Photoshop for many years. Lightroom since it's been out. I've always used a "Let Photoshop Manage Color" type workflow. I get the same grenish results as people have been complaining about, whether using the Gutenprint system or the Epson drivers (Updated with the common updater). I seem to remember that Lightroom had problems if color profiles (paper/printer profiles) were installed AFTER Lightroom. But that could just be my memory. Obviously, the color chain from either CS4 or Lightroom to the printer is broken. But how I am not quite sure right now. I may try re-installing Lightroom to see if that makes a difference.
I have been able to get fairly close color matching in both LR and CS4 with either the Gutenprint or Epson print system. But ONLY using a Colorsync workflow. (Letting the printer manage color and choosing colorsync as the method). Interestingly, a lot has been said about dark printing, but with Colorsync I see the opposite, prints are a little bright. More so with Gutenprint. Either system works close enough that until someone (Epson, Adobe, or Apple) fixed it so managing color works in CS4 or Lightroom, I can at least get pretty good prints. Gutenprint prints a bit bright, but it's such a feature rich system that tweaking that shouldn't be too much trouble. Still, it's not a good system (translated, simple, easy one or two click system) for most users. There's just too much to screw up and too much to set. But for someone willing to invest the time it will work fine. Colorsync printing produces results that are a bit flat, but seem to have pretty close colors.
Soooooo, until the color matching system gets fixed right, my suggestion for people is to let the printer manage color and use Colorsync. If I come up with better answers I'll post them here, and hope others will do the same.