Very interesting discussion and much of it beyond my ken, but will mashing longer at the lower end of the temperature spectrum with a relatively low pH optimize conversion for light lagers (as conventionally thought) or is there too much else to consider in the process to make this generalization?
I don't think anything here is refuting that idea. The question regarding limit dextrinase has always been how much of a factor does it play in the mash. Conventional brewing wisdom has typically held that it degrades too rapidly at mash temps to have much of an impact. Charlie's paper proposes that limit dextrinase may actually be a bit more stable at mash temps than originally thought, and that a lower pH may increase its activity.
Limit dextrinase, for those who aren't familiar, is capable of breaking down bonds in starches that alpha- and beta-amylase cannot (it breaks alpha 1-6 bonds at branch points). The issue is that limit dextrinase cannot access these bonds until the amylase enzymes have exposed them first. Since your typical mash rest is at a higher temp than limit dextrinase's peak activity, it isn't believed to have much of an effect on fermentability. If you can somehow boost limit dextrinase's activity while the amylase enzymes are also active, then you could see a boost in fermentability.
I have accomplished this myself in a high-gravity barleywine. I did an iterated mash, where I held a high beta-amylase rest initially, then pulled my grain bag and added more grains to bring my mash temp down to the mid 140's. The idea was that the second grain addition would supply fresh limit dextrinase to break down the dextrins from the first mash. While it is only one data point, I was able to get 83% attenuation on a 1.142 wort using a flocculant English ale strain fermented at 58F. I was quite happy with my results.