Originally Posted by
LesG
I've never used either with hot liquids so can't speak to that other than to say there is a high flow rate that comes out from both. I consider that a good thing. For hot liquids my guess is you'd need to be careful about how far you tip the bottle when drinking.
In comparing the bottles that burned lips to those that did not, aided by some reasoning, I can say that a direct connection to the bulk of the fluid, such as through a straight tube, especially a wide one, will burn. For regulating the temperature you need a transient container, with an extended lip most commonly used, where the heat can dissipate out. The flows from the bulk to the transient container, and from that container to the mouth, should be cut off at different angles. Then by regulating the pace of flow though the system and into your mouth you can regulate the temperature of the fluid that comes in.