I never cooked on a flower pot but smoke & fire is smoke & fire. I think your procedure is pretty good all though I cook at 300 and recommend it. Theres nothing wrong with cooking neked I've done it plenty and a Neked brisket is a beautiful thing, You don't wash your feet with your boots on you can't smoke in foil.
The two things that really stand out and need some work are keeping the pit closed already addressed in a previous post. Learning the "Feel of a tender brisket". Think about Hot monkey love and Hucka-Buckin with your woman for a second, Got it? Thats the feel! Once you learn that feel you won't even need to check the meat temp just before it gets to the givin up poking with your finger it should feel like a 16 yr old cheer leaders breast firm but yielding. You remember that and you'll be a much improved cook. I don't rest mine in a cooler I put it on a sheet pan and park it on the counter top, insert a thermo and tent it loosey, when the IT drops into the 150's it is ready to slice.
I never met a Cow that I didn't like with a little Salt & Pepper! Certified PORK-A-HOLIC