Double tensioner is similiar to the Brompton design as in 2 idler wheels. All cable routing is determined by the Bromptonesque fold. One of the facts of life in this design but I can't say that it has resulted in bad feel on my Bromptons. The steel plates are only there to guide during the fold.
The front rubber block is actually a front bag carrier that comes standard on the Merc but it is a $100 upgrade on most Bromptons.
My plan is to use this drive setup in combination with the rear hub and rear derailleur to have a 12spd Brompton. The brakes are going to be far superior to any of the factory Brompton's I have ridden. One general plus to all Mercs is they powdercoat the frames rather than paint them.