This is a very informative thread, to say the least. I have many printers in my studio, from Epson, HP and Canon. And the only printer that I can get to correctly send an untagged, no color managed target for profiling is my Canon IPF8100, which uses a Photoshop plugin (bypasses ColorSync I assume). I have spent more hours than I care to know, and in the end I threw my arms in the air and bought a new Macbook Pro 13", and am now using my old Macbook Pro 15" with OSX 10.4 Tiger just to avoid all of the hassles.
Printers that don't work with CS4 / 10.5.7:
Canon iPF5100 with regular driver
Canon iPF8100 with regular driver
Canon Pro 9000II
Canon Pro 9500II
The issue is larger than just Epson, it seems, and even though I needed a new computer anyway, most people are not going to be in the same position as I. I have no confidence in any output from OSX Leopard on any of my machines, whether it is a target for the creation of a profile, a 'real' color print or Advanced Black and White prints.
The problem seems to be hit or miss, based on conversations with friends that are all on OSX 10.5 Leopard. All are using Photoshop CS4. Different printers from different manufacturers.
I am going to upgrade my production desktop machine to Snow Leopard this week, and I will do some more tests. If early results don't yield anything different than before, I am going to keep printing from an OSX 10.4 Tiger machine.