I did a lot of research here and ended up buying two: the Sumtoy .562 and the Carlson .575 extended FL-Boss mentioned. This gun is a slayer with both with the #9 TSS.
Sumtoy pattern is pretty tight, I like it where I know my shots will be minimum 20 yds (open hardwoods/fields). Carlson is a great all-rounder for most reasonable distances. Both shoot exceptionally well.