I am so disappointed about the Roof Rack. This itemcost me almost $1,000. I took it to the Mercedes Benz dealer and confirmed itwas installed correctly. The rack stopthe sunroof from opening. But, most annoying, it has a horrible amount of windnoise. Even when the car is stopped.
If you're comfortable with modifying it, then you can make it so that the sunroof opens with the rack on. After reading your initial post on this I went outside and modified mine and did a quick test drive around the block.
Obviously you won't be able to return the rack to MB if you do this, but in order to make the sunroof open you just have to cut off the two little rubber bumpers on the front rack mounts. All it takes is a sharp utility knife. After those are gone, the sunroof can open. If you want the sunroof to open all the way, then the rear part of the rack has to be mounted as far back as it will go. Otherwise the sunroof will bump into the mounts in the back.
For the front bar, you should definitely open the sunroof first and make sure you have the clearance where you're going to mount it.
If you're going to use the bike mount, you might want to check the distance between the front and back bars and make sure it will still fit. I just use the rack for carrying wood, so I can't say if the bike rack or other attachments need a very specific distance.
Full disclaimers, blah blah blah, do this at your own risk, don't blame me if it doesn't work for you or you cut your finger off while attempting this, etc.