Al - yes - that article of Jeff's is indeed very good - I should have mentioned it, and good that you found it.
As for the 3800 - I've been using it for over two years. Best printer I've ever owned in terms of overall performance and print quality. Most of our displays are limited to an sRGB colour space, while the colour gamut of the 3800 exceeds Adobe RGB in some areas, but since your files are tagged ProPhoto, you have all the colours in the file which the 3800 can reproduce, and more. Don't be bothered by the gamut of the display. All it means is that some hues lying between sRGB and Adobe RGB would show in the print but not on the display. This isn't a train smash and won't prevent you from making very well matched prints provided the profiles are good and settings are correct.
Calibrate and profile your display with Spectraview and make sure (by going into the Advanced Properties - Colour Management section of your graphics card) that this profile is now the default profile. If for some strange reason it isn't, then select it from the list and make it the default however your graphic card firmware allows that. That means it will load when you open the computer. When you print, make sure Photoshop Manages Color and the correct paper and the correct profile for the paper is selected in the printer driver and in the Photoshop Print dialog. Make sure all Color Management is OFF in the printer driver. Before you make a print, do a nozzle check to make sure there are no clogged nozzles, and clean if necessary. The Epson 3800 is the first Epson pigment printer I've owned (and this is the 4th for me) which hardly clogs - a real relief. With all this, you should be good to go.