I would skip the sitka pack myself.
I am suspicious of gear marketed to hunters.
It tends to be heavy, dubious quality and with all sorts of added frills you dont need
Ive got many years experience with mountaineering packs.
Fit is key.
You can get a lightweight, comfortable, durable multipurpose pack for less than that Sitka.
Additionaly you have a much, much larger variety.
Mountaineering packs are designed for fast unencumbered movement, thats what you want.
Look at packs by Osprey, Arc'Teryx or The North Face (Profit series). Also lean towards models that have adjustable torso lengths.
I own many mountaineering packs, the one I'll use for my backcountry hunt(s) is an older North Face Profit 65. It wieghs just over 3 lbs itself and I can fit plenty in there. About 60 lbs is my tipping point for wieght/comfort.
Also in an emergency you can slip you lower body in the pack and provide substantial warmth...
One last thing, only you can answer this, is your sleeping bag roomy enough?
I have spent many nights in a bag that didnt fit right. If you get a lil chilly, and need to toss around a bit, if your bag doesnt let ya. Your not sleeping.