I have a few concerns :

1) this game shouldn't revolve around Purge, Magnum and horror. Not all guilds are capable of producing 10 players.

2) To further point #1, putting a class restriction would prevent many guilds from participating because of a lack of membership, able bodied players or a lack of players with skill and gear to compete. I think most non-pvp guilds are unable to furnish 10 players, let alone players having to fit into predetermined class restrictions.

3) If the time limit is infinite, 24 hour or something to that tune, what will happen during periods where Team A has 10 players but Team B only has 3 players? Will it becomes 10v3? Being that wagering is allowed, my concern is that the team who can keep their side filled with 10 the longest, will become the winner.

4) Is there going to be a bet limit? We all know some guilds and players can easily out muscle other guilds in terms of gold. We don't want to bankrupt people in a matter of weeks

5) Many people already complain about lag or frame skipping when there are too many people in one map. Won't 10v10 make this worse?

6) There should be a 5 minute timer at the start of each match that allows a team to forfeit, without penalty, in the event that they are unable to create a 10 man team.

7) Will there be a max damage limit per class so that lesser geared players stand a chance?

8) To add to point #7, would it be possible to scale everyone's stats down to be equivalent of the weakest over player of each class, so that it's a battle of skill and not gear?

9) My final and greatest concern is that smaller guilds will lose their members to larger pvp guilds.