I found it very informative.
BTW: I have two Sierra Designs LiteLoft bags that I think are just great!
Here's Tom...
All opinions -- never to be confused with fact!
Best Fibers On The Market
MicroLoft is another option. Its a recent DuPont release and is being used by the Thermarest folks in their new bag line, along with just about everyone who used to use Quallofill. Microloft is a "micro-fiber" that relies upon the mix of larger & smaller fibers to provide loft & insulation. Unlike continuous fiber bags (so Dupont's specs. claim), microloft bags will *increase* in loft as you use them. (Note, Caribou just dropped their Microloft line because they found something better -- see Primaloft)
LiteLoft, Sierra Designs only fiber, is a decent synth. that performs in this upper class of technical fills. It has a great loft and good feel to it. (The Polarguard bags are a little crunchy & stiff, even the HV bags). Its been on the market a while and is widely used.
Primaloft I and II are, in my opinion, the best synthetic fibers out on the market today. Primaloft I insulates better than down on a per ounce basis and has similar compression. Primaloft I is also a "micro-fiber" (like MicroLoft), but the denier is so fine that moisture has a tough time getting through it. If you want a damp weather bag, Primaloft I is better than a down/gore combo & much much cheaper. Primaloft I was pioneered by Caribou and is used by Caribou and Marmot.
Primaloft II - not yet widely available. I saw some of the Caribou bags at the OR show earlier this month & they were amazing. They loft up better than LiteLoft (the unquestioned former loft leader), and compress better than MicroLoft (almost as good as Primaloft I). Primaloft II does not have the water stopping abilities as Primaloft I, and is not as efficient, so if weight is the question, Primaloft I is your bag. Excepting Primaloft I, Primaloft II is the nicest synth. I have ever laid hands on. Its loftier than anything else on the market, weighs less (excepting Primaloft I), and compresses like a champ. I understand Caribou will have their bags out this spring and Marmot will have theirs out in the Fall.
I called Albany International, the maker of Primaloft, and they said that Caribou & Marmot have exclusive rights to the fiber, so I wouldn't look for any other makers in the US. (Given that, and Caribou's last ranking in the Backpacker survey, plus my old Quallofill Caribou that's done so well, I put my order in for a Caribou bag right from the company!)
Hope you enjoyed all that!