I think this is a great idea, it would help to build community and help to keep down the forming of cliques within FCs.

Of course there is the potential for selling runs, but this is going to happen anyway (apparently is already even) once groups have all the drops from Turn 1 they will sell the drops when they have to go each week. This will continue for all turns until they stop running coil, which of course won't happen since they can still sell the drops even after they have them all. So selling runs is no reason not to implement loot lockouts.

Actually it's the opposite, by implementing loot lockouts instead of character lockouts you will see FC members willing to redo runs to help other FC groups along the way, it will mean that FC members who can't fit into a static can still get FC runs, no more buying them, and the loot will go to them anyway. This potentially reduces the number of people buying runs, and in turn cuts into sellers market.

In the end, I'm all for this, as I would be happy to help people clear turns I've got done, if only to hone my own skills a little more.