Who is selling lighter underquilts?
I would prefer the suspension with the bungie cord running length wise, but I don't know the weight penalty for that preference. Hammock Gear sells them that way, but the grosgrain side channels are built to last, and weigh accordingly. Mike at Tewa Underquilts has light quilts without those side channels, and Tim Marshall's Enlightened Equipment UQs are 44" by 44". Features or size or weight, pick one.
Has anyone tried the "stuff it yourself" ones from underquilts.com? I believe that his are not tapered at the ends.
hammockquilts.com may be the winner by default.