I don't think I could stomach 400 Calories of sweetener in my bottles. 200 is about max for me. Normally I use 100 to 150 Calories per bottle.
I use 24 oz bottles and I finish a bottle every 50 minutes in temps around 75° to 90°F.
So we are kind of astounded that anyone puts 400 Calories in their bottles. Most just don't like the sickly sweet taste.