There is some difference in rotors,
I like the big wavy rotors as they do shed heat better or faster than the standard round ones.
Being a DH / free-rider and weighing in at 225lbs, I like good brakes. lol

That all being said, it's your first set of disks.
The BB7s are nice and will work well.
Ride with them and see if you really want / need the upgrade.
If you are not racing or do not need to have the absolute best, the standard 185s you have should be just fine.