For the kind of hunting I do a lot, I really like the Kelvin lite pants as a supplemental over layer. I'm generally a very mobile hunter (on foot), and usually hike my ass of each day. The key word with these pants is supplemental. They allow me to regulate body temperature, I can put them on when It's really cold in the morning, when the temp is dropping, or if I'm going to sit stationary for awhile and glass. I generally don't hike with these pants on, or if I do it's just a short walk to my glassing spot. I can also shed them pretty fast, which is great if I want to cover ground, or if it's simply getting warmer while glassing. Also, these pants don't have the same abrasion resistant exterior as other Sitka pants do, again they are for supplemental warmth. As for long johns, I personally have found the heavy weight bottoms to be too much, but again I'm moving a lot and I get hot easily.
I don't own the Sitka blizzard bib pants, but If I happen to be hunting from a quad in November I do have heavy duty insulated bib pants for that very purpose. Wind chill can be brutal when driving around.
I guess it all depends on what kind of late season rifle elk/mule deer hunt you'll be doing. Is it from a quad, truck, or on foot? Do you need layers that you can shed quickly, or do you want something warmer/heavy duty? As for hunting whitetails, I haven't had the opportunity to pursue them, so can't comment on that one.
