OT for sure Ted...I've emailed my data and reached out to you and never hear back so this is the only way I can engage you to discuss some other interesting oddities.
Breaking the 350 series backs into groups (sheet mates) based on cards that are only found with the same backs with no exceptions....you start to see patterns.
Like your Elite 11 pop right out - Groups 8 (3), 18 (3), 24 (5) = 11 + Group 19 (Lundren)
Those in Group 4 (9) I mentioned are in their own group and are all still unconfirmed for Sov350s....leading me to believe they do not exist. There are several more subgroups if you start to group the unconfirmed groups.
I think we can knock off most of the unconfirmed cards through this method.