Dammit Erick, now we're going to get a detailed discourse on why re-using drink bottles is bad for you because of the leaching of some chemical that only occurs after the bottle has been opened the first time.

I've never seen a need for metal bottles. I use Zefal Magnums and I like them.

I have one of the Topeak extendable Modula cages, but have issues with how the top[ of it moves around a lot, and I fear for the durability of the mounts. Experience of others may show differently.