I think it depends on the malt used and if it has a bunch of Alpha and Beta. The studies that Kai and Greg Doss did for Pils malt said 152-153F gave the best attenuation. There are data that say lower is better, maybe for Pale Ale Malt with is low in Alpha. For "hot" US malts with high Alpha and Beta, it might be around 158F, but that is speculation on my part.
Waiting for my copy of Malt to see if Mr. Mallett covers this.