A lot of my backpacking in the Sierras involves a backpack to base camp at 10,000 or 12,000 feet.
Overnight then a day hike to bag a peak.
Another overnight and then home the next day.
On peak-bagger days in the past, I've emptied most of the contents of my backpack and used that for the day. This is not ideal because my 80-liter backpack is bulky, awkward, likes to snag in tight places, and is heavier empty than I'd like.
The Flash 18 holds 18 liters and weighs 11 ounces. My regular sleeping bag stuff sack weighs 3 ounces, so I added net 8 ounces to the load up to base camp. But at $34 it's worth every ounce. I picked mine up on sale for $18.
The straps are light but comfortable and keep sweat from accumulating.
The sternum and waist straps keep the pack well-adjusted and tight to the body for better balance and minimum clearance
in tight spaces.