I bought my wife a Swobo Sanchez, so I'll play nice.
You have to prioritize comfort. Weight is obviously a factor for your situation, but here's how I see it. If the bike is uncomfortable, it's not gonna be very motivating to ride. If you're not motivated to ride, you're not gonna be motivated to lug it up and down 11 flights of stairs every time, regardless of the weight.
If it's a joy to ride though, you'll jump through hoops of fire to ride the thing. So get your priorities right.