Matt, I can give you some feedback on the Big Agnes bag system, rather than that particular bag, so I hope this is helpful.
Since the BA bags are "quasi-quilt", meaning uninsulated on the lower side, but still a full envelope, you can get a bag that comes out pretty light since it relies upon your sleeping pad for under-side insulation. This does presume you carry a sleeping pad, and the BA bags will only sleeve a 20" or narrower.
One trade-off effect with the BA system is that if you "sit up in bed" (or the tent), the air mattress has to come with you. That was odd and took getting used to.
I use a Mystic SL, because it's light-ish and is cut wide. The lightweight zippers BA uses regularly jam. This is occasionally so annoying that I am known to remark "this is the last #$%@ time I use this bag" right after I have to swim an arm out and then burst the zipper to get out of my bag. The YKK's do self-repair (at least 10 times so far) and a new bag is expensive and I have a short memory... I suggest you visit an REI or other store and use the zippers from inside the bag, over and over. The larger zippers in a non-SL-series bag might not have any problem, and my wife's SL bag/finesse haven't had any jams. I'm just suggesting you check it out.
The pillow-sack inside the hood of the BA is handy. My down puffy lives there in warm weather.