Hey guys, I own/run DIY Gear Supply.
Everything in this thread looks to be about exactly right on the money re: Insultex. Tim is the VB expert, listen very closely to anything he says in regards to Vapor Barriers and quilts.
Honestly, though I do sell a lot of Insultex, I do not recommend it for top quilt use. And I don't recommend it for most average DIY'ers too. Unless you really know your stuff around vapor barriers and how to use them properly, you're not going to enjoy it, just going to feel clammy. Climashield / Primaloft (and even better, Goose Down) is by far the better way to go with top quilts for 95% of us out on the trail.
I would, however, recommend it for underquilts (in hammock use), where moisture regulation is not such an issue.
And even better, where I feel it shines, is in conjunction with a synthetic loft insulation like Climashield. Insultex does a great job of keeping the heat in the loft of normal insulation materials - all those micro-cells significantly slowing down heat transfer, and and the closed-cell nature of it eliminating heat robbed from wind.
But again - keep the vapor barrier qualities in mind on any project design.