It worked really well. The air popper worked, but it was too hard to keep the rye in it, it flew all over. Then I tried a microwave popper and that worked a lot better. Just for differences, I tried a pan with a thin layer in it. That worked well too, but added some toasting.
All methods opened the rye up just a little bit.
Efficiency wise, I used a single infusion mash and got the same efficiency as if I had completed a full cereal mash, so it works.