I've been struggling with bottle over carbonation, too, and I'd like to know how much the head on a "typical" pour is reduced if I reduce priming sugar by 10%.
I've been doing lots of forum research and concluded the temperature that goes in BS is the temperature at which you were fermenting just before the beer goes into the bottling bucket. This tells Beersmith how much CO2 is already dissolved in the beer because, as KellerBrauer says, dissolved CO2 depends on temperature. Now I wish I'd copied and saved the posts that explained that.
Also, if you mouse over the temperature in the carbonation profile, you get a little pop-up, "Temperature of the beer when bottling or for storing a keg".
Further experimenting with the carbonation profile set to 2.2 vols and 65*, gave me 3.16 oz table sugar for bottling vs 1.58 oz for kegging with priming agent. Why would that be???
I used to think that the temperature to put into BS is the conditioning temperature, but this seemed counter intuitive because all of the sugar is going to ferment out as long as the temperature is withing a viable range for the yeast. The resulting CO2 has to dissolve into the beer or explode the bottle. We don't get bottle bombs by conditioning at too high of a temperature. We get them by not letting the beer fully attenuate and/or adding too much priming sugar.
I hope this adds a little value to the conversation.