I actually collect Siggs.
: I have a lot - from .6 ltr. to 1 ltr., and I have some knock-offs they sell in places like Woolworth's in Europe and Wal-Mart here. Some of my authentics I don't use at all because, like I said, they're part of my collection, but I always have my Sigg next to me for frequent sips of water all day long. I literally go nowhere (even in the house) without my water. I love them!! I also like the insulating sleeves for them. Dd carries one of hers around, too. She has two .3 ltr. and three .6 ltr. Her current favorite is one with horses on it.
: She also has Felix, Benjamin Blümchen, Die Maus, and one with flowers. It's a great way to get kids to drink lots of water. She loves them, especially with the sports top. She used one as a sippy to learn how to drink from a sippy cup (you can get them with handles).
I've never had any real Sigg break, the lining to be compromised, or the outside paint to chip. I only use it for water and I also use the "bottle clean" tablets to keep the bottles fresh. Yeah, if you drop it, it gets dented... but that's a good used Sigg.
The knock-offs will chip, dent more easily, and may or may not have the enamel coating inside.