rake is a complete killer in many games. If they have their agreement between themselves there should be no problem (actually more strength to them I say).
What would be interesting is to organise games at the penny limits on
pokerstars ( no rake to $1).. the agree that every penny = $10!!
I think on
Pokerstars that if a table agreed to do this in chat then
pokerstars would actully endorse/make all the neceassry transactions for you.