Ok, why not have a whole bunch o' kharnes?
See, the issue is here: They say they are Arche-types so The green marines can field a tigerious.
Spirit of the rule time- Kharne the Betrayer is marked as Unique. You can only use one per army. Last year, only one person could bring Kharne as per the house rule.
Using the Archetypes rule, you can field Marneus Calgar and still try to be fluffy in a yellow space marine army. Just call him Carneus Malgar.
So, why not limit characters just like last year. Only one person can field each character.