What i have learned-
Rugby World cup game Produced by HB Studios and Published by 505 games; will have the better/most Realistic Gameplay and Great Visuals. They have so far only announced that they will have the 20 World Cup Teams and obviously they have the IRB's backing for this game. Hopefully they announce another tournamnet or 2, because HB have the experience. They Produced The EA Rugby Series which stopped in 08' for PS2 and PC. They have also co-developed with FIFA's team in Canada on a couple of occasions over the last 2 years or so.
The Sidhe guys from New Zealand do not have too much experience; i think they might have been involved with the making of The Rugby League games, but those games are poor even compared to EA Rugby 08' which came out in 07'. But, they do have the "Exclusive" rights to Superugby, ITM Cup, New Zealand and Australia.
My Bet is on HB to make the best Rugby Simualtion ever created; but won't quite have enough licenses to make it good "Longevity" wise. But, i will Def. be going for Quality over Quantity. HB have also hinted at Starting a Series again, and this Rugby game will Set a Great Platform to Build off. So Chuffed it is on 360 and Ps3, Awesome. Go HB Studios and 505 Games!!