I don't use Sigg bottles for drinks because they are too similar to fuel bottles, particularly in the dark. The interior of the bottles is coated (you don't want uncoated aluminum bottles because acidic drinks will react with the aluminium), but the description from REI says: "Interior coating will not leach into fluids; bottles can be refrigerated but should not be frozen", so they are not acceptable in winter.
Sigg used to sell them as fuel (unanodized)/drink (anodized) bottles ~30yrs ago and then they disappeared from the American market (at least I didn't see them) and are now back.
Sigg is no longer marketing them has fuel bottles, but the old ones had the risk that if you pumped them up too hard, a weld could crack spewing fuel out right next to a burning stove. And they still feel too much like fuel bottles in the dark...
My suggestion is that you stick to plastic drinking bottles. I use 24oz soda bottles* in summer and Nalgene HDPE or polyethlene wide-mouth bottles in winter.
* My experience is that soda bottles are much more robust than bottled water bottles (at least for the brands that I tried). The bottled water bottles are of a lighter construction and would begin to leak after several days.
Doug