I spent some time testing a ColorMunki. There are issues with SL, but it appears you can produce an accurate target by choosing Epson Color Controls in the Colormatch dialog box, but turning Color management off in the Printer Settings Dialog. If you leave the default to ColorSync in the ColorMatch dialog, the target will definitely have a problem and the resulting profiles very limited gamut.
In most programs, such as Photoshop, this isn't possible because the ColorSync/Epson color Controls buttons are grayed out.
Bill Atkinson's Lab Test page looked terrific and there were no significant differences between one printed with the canned Epson profile for my 7900. I did a little
write up including a Colorthink graph comparing the ColorMunki Profile to the canned Epson one if you are interested