Paul, I get the basic idea re: surface to volume ratios... Im just not seeing how the amount of air trapped inside the Delta fiber can possibly equal the amount of air space created by an insulation that relofts quicker. Yes, for the very short term, the delta would be holding more warm air. However, in the long term, the faster lofting fiber would seem to create more air pockets by weight.
In light of the fact that Delta has a greater surface area which would expose more area to cold temps (in example, the water) and heat more effecntly radiates from hot to cold areas... It would seem that if the insulation remained in direct contact with cold enough moisture (which may not need to be THAT cold) any heat trapped inside the fibers would be drawn out into the moisture and away from the trapped air.
With the double whammy of slower reloft and increased radiant area....
This isnt to say that a new or well cared for Delta insulated item wont serve the user very well... but I, personally, would be loath to use a delta item that has sustained any hard use.
As I said, my research hasnt given me good vibes on Delta.