Well well well, I'm not sure why this is even being discussed as most League players don't have the patience, work ethic or brain to succeed in rugby. Take a look at the Superstars:
Hayne - the most overrated player in League, had a sensational 8 weeks of football in 2009, didn't stand up in the final and has been terrible this year.
Thurston - I don't think draw and pass can get you selected as Wallabies Flyhalf.
Iglis - Lazy, big ego, and I think you would find he would have a very low work rate in rugby compared to somebody like Horne or Fainga'a.
Smith - What does this guy actually do apart from kick shots at goal and cheat the system? Genia is a visionary genius compared to this hit 'em up player.
Lockyer - See Thurston
The only current League Superstar that I would be inclined to persue would be Slater. Fast, takes his opportunities well, works hard on and off the field, isn't a tosser and his skills are more adaptable to the back 3 in rugby than other positions in league.
But forget about the Superstars, some of the smaller names would be better investments as their code switch wouldn't be money fuelled - see Will Chambers success at the Reds this year. Brett Morris and Hindmarsh come to mind.