As they say, information is NOT knowledge. I wish one of our scientify members would finally put to rest the idea that insulative value = loft only. 3M has been marketing Thinsulate since before many of us were born. It achieves its insulative value with fine Olefin fibers that reduce the size of air spaces in the batt. OK, it's much heavier than down, but the point is that the insulative value is not governed solely by the loft.
Despite the weight, I do prefer Thinsulate booties, because they take up little space, there is no danger of loss of loft, and they still function when moist.
But I would know better than to argue with downers, especially DWR downers.
The concern is that I depend on the booties to avoid cold feet, and don't want them to get wet on nighttime forays, mostly because if wet, the will soak the interior of the down bag. If I take them off, I've lost the whole benefit of bringing them – warm feet when the temp unexpectedly drops below the insulating capacity of the bag and sox.
So Doug's post about the Goosefeet Over-Booties looked promising, although the 1.7 oz is for a medium. But Goosefeet don't state whether the weight is for one booty or one pair, an issue that seems to come up too often on these pages. Also, the light sole is Dyneema, which is of doubtful traction. The optional Toughtek is over twice as heavy, and it's still not clear whether the weight is for one or a pair, and what if any slip resistance is on the sole. There's no photo of the cover or its sole.
So once again, it's back to MYOG. Maybe a thin convoluted EVA sole made with a hot wire foam cutter, bonded or sewn to a 2 oz water resistant balloon cloth upper with a zip closure (It's pouring rain, the ground in front of the tent is irregular and slippery, and I'm groggy with fatigue. It was a hassle getting on the wet rain cover. Now I have to tie on booties? Mercy!) (#3 coil zips weigh only 0.1 oz per running foot – #5 about 0.25 oz.) Once up and outside, the rain is actually refreshing for a few minutes.
EMS once actually had a booty/cover combo item like this, but long since discontinued them. They sold out before I could grab some in my size.