this will take some time to determine, primarily because raids are 4-5 and in some cases 8-10 times the difficulty they were before c5.
each boss is also different as some bosses go bananas when they get down to 30% health or lower. others not so much, also respawn on the assistant mobs is increased in some cases up to uberfast.
all in all youre looking usually at a 3+ party raid.