I don't hold the view we're too good to play these sides and personally I love the idea of inter league games but the dates don't suit us (and its not really inter league anyway). If it was an end of season thing for us I'm sure we'd put out a decent team. The whole amatuer/professional thing is a red herring too and most players in the first division here receive some sort of pay.
You say it should be for the highest level, I'm asking why you think that, and do you not think it would advance the players more if they were all u21?