If I had one of these beasts, I would probably call Korky and double-check whether the 5030BP Adjustable 3" Flush Valve and Flapper works with the Champion 4. I might even see if they'd send me one if I would review its installation ease and effectiveness on the Champion 4, as it is a new product. Installing it would require pulling the tank, which I have done a bunch of times so it's no big deal to me, but it's not as easy as replacing a fill valve. Then you would have a nice standard Korky 3" flapper controlling the water exit from your Champion tank.
If the thing is designed to fit the Champ, I personally would rather have a nice, straightforward 3" flapper instead of the doofy "Accelerator". (The Champion "4" has a 3" flush hole, if that wasn't clear...)