Currently nothing in my Rem 870 SM, It was setup for a Jellyhead .660 and Magblends, but i've gotten away from the Hevi shells and have gone back to all lead. But it does toss a mean pattern with the TruGlo SSX .643 and the Thugs. Also have a look at Winchesters new Longbeard shells. I have a lot of testing myself to do but I can almost predict what is going to shoot well from this gun.
If you want to go the custom route give William at Sumtoy a call, he can make anything you want.