As it turns out I was worrried for nothing. I replaced the original HB triple with the Atra double blade, and it works beautiful. I get a clean close shave with little irritation.
The atra has a good feel and I am getting about a week's worth of shaves.
I also have been using a generic atra double for my cleanup and face, with those I found I need to change up a little sooner. I do like the Mach III better for cleanup, but for getting in tight around the ears, the thinner double does the trick.