Blake,
I've got a demo HighLite you're welcome to take out for a spin sometime. I think ericb sums it up well. If you like the fit of the HighLite you'll probably like the bag. If not the MontBell Super Stretch is a great system. Western also has the Caribou but it's not 16 oz. I find the way the shoulder and hood closes on the HighLite to be a bit more restrictive than other Western bags of the same shoulder girth (59") like the SummerLite for example. Just a bit.
We also have some interesting down bags from Macpac. Waterproof/breathable seam taped shell fabric, and I think the Epic 150 (note: not Epic fabric you might know) weighs just over 1 lb. Sky and a few others have used my demo. The others (WM, MB) seem to be warmer but not waterproof either.