AJ,

If memory serves, when the squish band first came out it was to enhance the burn pattern on high performance glow engines using FAI (no nitro) fuel. Now, it seems that many sport engines use a squish band with nitro fuels. Not sure of the necessity.
Perhaps studying heads from performance engines that have both high nitro and FAI heads available might help.

Interestingly, it was the Fox Eagle .61 that had the flat squish band.

I have NO IDEA how the burn patten of diesel fuel is affected by a squish band. I have never heard(seen) a complaint about the heads you produce. I would suggest, whatever you are doing...keep it up.

George

Edit: AJ, I just reread your post. Do some of the contras extend below the squish band? It would seem that if burning fuel was "trapped" in the squish band, it would not be scavenged out and may cause a heat buildup.