Richard N. reports that the clo value of the micro puff polarguard delta insulation is higher than that of montbells exceloft, so naturally the puffs are warmer. (and much heavier at 397g vs. 281g). They have about the same ratio of insulation/weight. My suggestion is to calculate the clo of each product using Richards previous posts...Or, buy for a feature you require. For example, I have the montbell thermawraps(3/4 zip), but I need full zip for alpine trips, so I am buying the micro puffs.
edit:thanks for the info/correction, Jason.