Ultralight with Options
This is a fantastic bag, albeit slightly fragile and unsuited for off-trail scrambling (the mesh backing will be the first to go). If you want a bag with lots of options that won't force you to make your kit completely ultralight this is a great start. Osprey has tons of bells and whistles on the bag and the inside out compression system is top notch.
The floating pocket can easily be removed to slash 4-5oz off the base pack weight (which is nice) and I've yet to need to reattach it as this bag is much bigger than its specifications suggest. I wear a large pack and a spec of 61L definitely undersells the bag. The silver color on the bag is also a big plus as it makes it tremendously easy to differentiate between items.
I wouldn't use this bag in winter as the rip-stop nylon simply soaks up water from the snow but if your mission is 3 season trail hiking/climbing and you want to shed a little weight from your back without surrendering full comfort, definitely go for it. If you're really looking to go lightweight, attack your kit first and then get THE BAG to fit it.