I'm a Guyot convert. Used Nalgene for years, dumped the fleet of them after I bought a couple of test bottles from Guyot directly. That said, I very much favor the 40 oz, "standard" bottle. I have a backpacker as well. But unless they're going to be in a car drink holder all day, I can't see giving up that extra stability (and they are slightly less stable), nor the reduction in capacity. My standard guyots fit my OR covers, the SS cups, and everything else I had to go with my nalgene fleet. After my test run, I turned back around and ordered a dozen for my fleet.

True enough, the SS cups can be used in fires. But I sometimes like a warm drink with my hot meal. A SS cup AND the guyot are the perfect combo for me.

And I've carried 2 full hiking for hours. Are they noticeably heavier...absolutely. I just prefer them and love the adaptability.

The cons:

1) they are heavier. I'll manage. The tradeoff is that things stay a lot cooler even after baking in ahot car for 6 hours. I add a lot of ice and drink and I often have ice when the car has been in the sun superheating for 6+ hours. But if weight is your main concern, it may not be for you. I carry these all day almost 6 full days a week. If I'm going to be away for a while I carry two.

2) They're metal and will ding up a bit. I've never had them compromised after about 3 or so years of HEAVY use and ABUSE. I say this as someone who broke 1-2 Nalgene bottles a year.

3) I'd love to see them do something with the tops. An inert, safe material with some sculpturing would help a LOT. Since they can get a bit of a vacuum seal when opened hours later, and opening them wet is common (weather, from a cooler, etc), it would be a nice addition.

4) Made in China. For me, this is the biggest single drawback. I'd love to see them made in the US...or even India.. but CHINA? When I bought in, hardly anyone was making SS bottles and those which were available had a much less desirable design. YMMV...

Now my question from the readings above...do the filtertops actually fit the Guyots? I've yet to try this and would love to know.