I've been running a sawtooth since 2008 and for me it is a solid 25* bag. 15* Is a little cold but it has held up great to a lot of nights in it and I have made the cardinal mistake of storing it 'stuffed' for a few weeks at a time so it has lot a bit of loft. There are lighter options out there for the weight but don't kid yourself, it is a quality bag and would serve you well for Sept/Oct hunts.
steepandcheap.com just had the sawtooth on today for $169, although i googled it and somewhere else had it on sale for $175
cant help you with your question, never used one, but almost bought that sawtooth today until i saw the weight, decided to stick with my sierra designs arrow rock 15, which by the way was on closeout sale at STP recently and slightly lighter than the sawtooth, but not sure how they compare
I am sure Aron will answer up , but I just picked up Extreme Elk Mag and Aron has a budget section and list the Sawtooth as a good bag
I have been thinking about a new bag and the Sawtooth is on my list also.
Like already stated it is not as compressable as the 800/850 fill bags. However, it is a very very good bag. Especially now there are some excellent prices that can't be beat.
I have arranged testing of the Kelty DWR down 16 EN bag later this spring. Retails under $200 and weighs under 3 lbs. Can't vouch for it yet, but sleeping bag tech is trickling down to lower price points.