Well,I don't cook on a 500,but have watched them work with great admiration.
We do cook on FEC 100 s.
Size/weight will probably be your guideline.
Is your stickburner reading 200º at the cook surface?
The 500 will cook right on the setting,with somewhat of a convection effect.
Depending on if your loinbacks are 20 0z,or 2 3/4 lbs,will change the system a lot-but seems like 3-4 hrs will put you in the ballpark.
Large breast fillets probably work at that temp in under 1 1/2 hrs,but larger pieces will probably take more temp,or time.
Butts will tend to run more like 1 1/2-2 hrs per lb,to get to pullable.
At 200º pit temp,it would depend on if you were trying to get to a chopping,or slicing internal temp- if you need to foil.
I would guess that unless you need to cook at 200º,they will suggest you cook at a little higher temps.
Foiling might then be a question of speeding up the cook.
Some stickburners like to foil to prevent oversmoking the bigger meats,but the FEC s burn so cleanly that it isn't necessary.
Go up to the FEC forum and shout for Fast Freddie.
He is giving a 500 a pretty good workout.
Seems to me there used to be a Hot Thomas and a couple other decent bbq joints around Watkinsville.
You related to any of them?
Hope this gets you started,until someone else stops by.