I'm willing to give up 150ml of capacity and opt for the Snowpeak's excellent packability with a Nalgene or Gatorade bottle nested in it, while saving $13 along the way. Not that you can't nest a bottle in the Ti Kettle, just that it's not quite as efficient.

Part of my reasoning is that I've had great results using the 700ml Snowpeak for a party of 2 hikers, so I know for me it's enough volume. If you bump up to 3+ in the party, or start needing to melt snow, the 850ml capacity doesn't help much over the Snowpeak and you still have to go to a larger vessel.