Here is the Math for a single protein buffet...
400 portions X 8oz portions Plated = 3200oz / 16 oz per lb = 200 Lbs cooked / .6 %yield = 333 Lbs Raw Needed.
I don't know the make up of the guests. Men, Women, Children? But Men will look at anything less than 8oz as a Childs portion. If it is self serve men and teenage boys will take closer to 16oz Meat and skip the sides. I have catered many events and never seen anything other than a Ladies Luncheon go under 8oz portions. With a single plated protein, 8oz is common as women and children will go light leaving extra for big eating men and teens. Think going to a Restaurant, the PETITE Prime Rib is 8oz cooked with the 16oz and 20-24oz King Cut being the standard size, and thats with generous scoop of Veg and a Baked Potato the size of your Fist on a separate plate!...Good Luck with the new smoker...JJ