I have an E92.
I bought and use Thule roof bars + 591 bike carriers .... rock solid and good quality. The bikes lock to them and the bars lock to the roof.
I have used them about 6 times and they are taking our bikes from Surrey to Norfolk in a month ... and I am more than happy to trust them.
I have used boot carriers before and ended up with a dent in the top of the hatch on my Golf as a result of not adjusting it correctly (Saris Bones rack). You can't really go wrong with the Thule bars so long as you don't drop the bike on the roof when putting it on or taking it off !!
I would certainly recommend the Thule bars and carriers.