I finally bit the bullet and had my transmission fluid changed to Transynd. Took it to a reputable Allison Authorized service provider and they said they purged the trans cooler and torque converter (I'm going to send a sample to be analyzed to be sure). The problem: I noticed a slight difference in shifting smoothness, but no difference in running temperature. With standard fluid it was running 185-189. With Transynd, it was the same. In fact at one point today it got to 192, which it never did with the Dexron III. This was level road and not even close to max weight on a warm, but not hot, day. And fluid level is on mark according to the keypad check.
Maybe I had my expectations set too high. I was really hoping for reduction in ruining temp. Anyone else have a similar experience?