Can't help with the bottle, but what do you think of your soda stream?
Oh, I love it. My husband drinks a lot of soda, and I drink a moderate amount of carbonated beverages in general (especially seltzer), so it's cut down on cost (slightly) and recycling (in a serious way). The convenience factor is great--never caught at a dinner party or a late Sunday night without easy access to the drinks we want.
The flavors are hit and miss. If you're a Coke fan, cola is never going to taste the same. That said, their version of Coke Zero is, I hear (again, from my husband), not bad. I don't love their Diet Coke version, but I like their Diet Dr. Pepper stand-in and absolutely enjoy the root beer, cream soda, and cranberry.
Honestly, I'd do it for the recycling space alone. There are other bonuses, beyond the things I've raved about: you can custom-carbonate, meaning one person can have flatter soda and the other bubblier; you can make your own syrups; and there's a lot less sugar and fewer calories, even in their full-sugar syrup versions.
I'm mostly just whining about the bottles, for the record. I know I'm not supposed to use boiling water, so I've resisted any temptation. Generally I use warm water and just swish everything around; sometimes I use my bottle brush, soap and slightly warmer water. Today, after my whining, I did a thorough scrub with the bottle brush and soap, rinsed, and then did another rinse with diluted white vinegar. I have absolutely no idea if it helped with anything, but I did feel very Heloise about it--I don't know if it's more clean, but I
feel like it is.