I suppose I should update per the current UA model lines:
The Gunpowder is still the warmest of their lines, but they've combined the Dead Calm and the Rut Scent lines together to create the "Rut" line (the only significant difference between the DC and RS used to just be the waterproofing anyway). They've also eliminated their Ridge Reaper line and consolidated the Ridge Reaper and Ridge Reaper Infrared lines into the Speed Freek line. The Ayton fleece is still hanging on strong as their low-tech, budget friendly early-mid season gear.
The Gunpowder is the only "water proof" system in the line up (the Ridge Reaper Bibs used to be as well, but again, discontinued), and is the only lofted insulation system in the line up as well. As such, they're the most bulky, warmest, least breathable, and least quiet of the bunch. The Gunpowder used to only be a distributor exclusive (Dick's Sporting if memory serves?), but it seems that they've expanded that offering to a broader distributor base. I tend to compare the Gunpowder to traditional down insulated Goretex gear, whereas the others are more related to those black North Face jackets crossed with the suede/fleece like Columbia jackets running around, if that puts a perspective on them. The Ayton's, of course, are just lined fleece, and actually make a great affordable system themselves, even if they need a lot of under layers when the wind is high and temps are low.