Getting back to the question of DOW LP-4040 membranes
After a few emails with folks at Dow, nobody would say why one spec says it is better at low temps and nobody would say better than what other membrane at low temps.
The key seems to be to expect 3% reduction in perforance for every 1 deg C drop below 25. So we should expect a drop of 50 to 75% ..... before we get a build up of crud.
And about warming the sap ... keep in mind that the max operating temp of most membranes is about 115 to 120 degrees. Check the specs on yours before going down this road too far. This is why the cut off temp for cleaning is pre-set.