I have been using the Deuter Speed Lite 20 for over five years now and find it to be the right pack for everything from grocery shopping to fast and light alpine climbing.
The pack's features seem endless as well as its capacity. It's a 20-liter pack, but with the side straps you can attach ropes, jackets and even the Deuter External Pockets to maximize storage. It has a piolet (ice axe) holder that is actually made to hold a piolet and does this very well. It comes with helmet holder attachments, but I usually just use the side straps for holding my helmet.
Deuter rates the pack high in all categories except trail running and travel. I have found there are better packs for trail running, but I still like this as my personal bag for travel.
I use the pack most for multi-pitch rock climbing, as the straps adjust to keep the profile small but the 20 liters is more than enough for jackets, food and water, first aid and sometimes a second rope for rappelling.
The pack performs well for resort skiing and light/fast ski mountaineering. The side straps hold skis well and the pack is light to keep you out of getting thrown into the “back seat.”
Speed lite is an alpine master, comfortably hauling cams, crampons, food, water and an extra jacket. With its ability to accommodate side packs adding up to 10 liters of extra room, it will be up to you to how far you want to push it in the big mountains.
You can find my latest trip report with the pack here.
The Speed lite 20 is also my go-to pack for mountain biking. While Deuter makes some great packs for biking, I only have so much space in my closet. So I use this pack solely for all biking pursuits. With the Deuter Streamer hydration pack and easy-access mesh side pockets, it keeps you moving longer without stopping, which means better workouts and more fun.