Hey all, I just noticed this topic; chiming in to recount my experience—I did fabricate a "Franklin baffle" for my tiny backyard offset, here's a picture:
You can see it in action here:
https://youtu.be/wCGwfvNFpFE?t=42
My smoker is a 16x36 CC with a 16x22 FB, and ø 4.5"x30" stack 3" above grate level, a Cactus-Jack 16" Longhorn ProSmoke edition; think classic OKJ with an oversized stack. It comes from the factory with an angled baffle just below grate level, and it used to give me a considerable hot spot in the middle of the CC, where a brisket point would sit. The factory baffle also obstructed the top third of the exchange (football shaped, two overlapping circles).
I thought I'd give the Franklin-style baffle a try and fabricated one—temps are now much more even across the grate, except right in front of the baffle itself which of course goes nuclear. Using this baffle also opened the throat completely going up to 74 sq in, which is slightly more than double the recommended amount (about 34). I'll realistically weld some rebar on the top lip because it tends to bend and deform slightly under the intense heat (though this might be a good thing and add to the turbulence, who knows)
I'm a tinkerer, so I gave the Workhorse-style exchange a try as well: the top half of the throat gets covered by a half-moon plate, and a short, detached lip extends 45 degrees downwards into the cooking chamber—this gave me very, very equalized temperatures across almost 7/8 of the cooking grate but I could see the heat waves coming off the stack with less energy
If you've got questions I'm happy to try and provide an answer
