-- respawnitem on by default for Cooperative games. Currently, if a player grabs rings and dies, those just totally go to waste and the rest of the players are screwed. This is especially applicable to ERZ, where rings are sparse in some tricky sections. Besides, items come back when you die in SP, so why not respawn in Coop?
-- Turn off the "perfect" bonus in Cooperative games. Without respawning items, nobody will get it assuming at least one other player grabs a ring, and with respawning items, it'd be possible to illegitimately gain the bonus.