Hi Ken,
I've been using the Atkinson profiles for over 6 years with two 7600 printers. The profiles have always performed as expected and I've produced some excellent results with them. And as one other post suggested, your issue would seem to be systematic. First of all, AdobeRGB 1998 is a working(colour) space, not a printer profile. However, if you have been achieving good results with it, I can't knock it. I'm wondering if you have read all of the accompanying literature that is downloaded with the Atkinson profiles and if you have completed all of the setups required to help the profile do its job properly. It might be a good idea to go back over those setups and make sure they are indeed correct. It still sounds like a matter of double profiling to me. In other words, you MUST make sure that when letting PS manage colours, the colour management is turned OFF in the driver. And by that I mean in the final print dialog, under Printer Settings, NOT in the area where you chose Printer Manages Colour or PS manages Colour etc. There is a selection there for No Colour Management, but it's used mainly for printing profiling targets. DO NOT use that setting! Also, make sure the correct Media Type is selected, according to the profile literature. And of course the wrong Rendering Intent can definitely have an adverse affect on the outcome as well.
There are a lot of us who have used the Atkinson profiles successfully in the past, and I still use them on one 7600, so unfortunately it would seem that perhaps something in YOUR setup is amiss. If you are satisfied with your current workflow and its results that's really all that matters, but if you want to solve this issue I would strongly suggest that you retrace your tracks in the profile setup department.
Gary