The beauty of Lotus' device of which I'm coining DRD (Drag Reduction Device) is it doesn't need DRS in order to work and reduces drag at a certain threshold. This means unlike the Mercedes DDRS system it will reduce drag even when DRS isn't available during the race.
4. Periscope: This is most important aspect of the whole system as it's how the air is transported to the underside of the Rear Wing in order to create the additional downforce at low speed and 'Stall' the rear wing over the speed threshold. In the picture below Lotus had the ejector holes taped over in order to stop the device operating (due to bad weather conditions)
In the images above we can see that air consumed by the Airbox 'Ears' is transmitted along the top pipework and branches off to the Periscope. In the enlarged image of the Periscope we can see the ejector holes that blow air tangentially across the width of the Rear Wing main plane (The image below shows the effect of this when the team used flow viz at the Hockenheim weekend), blowing the underside of the wing reduces boundary layer build up which allows for a steeper Wing AoA to be run giving a net downforce gain. The amount of rear downforce available to teams has been reduced since the regulations stopped blown diffusers. Making the amount of downforce generated at the rear wing once again imperative.
At a certain velocity the amount of air being blown isn't enough to prevent the boundary layer build up and the wing stalls. (CL Max) This reduces the amount of downforce and drag on the rear wing.
Simultaneously the air in the periscope now creates a blockage which allows the airflow to feed out toward the Monkey Seat / Mini Diffuser which will increase it's effectiveness creating downforce in this region.
The switch from downforce creation to drag reduction is aided by the use of the Monkey Seat / Mini Diffuser as it helps transition the forces involved.
So far all I have shown you is the Lotus variant but during Free Practice on Friday Mercedes also placed a similar device on Nico Rosberg's car. The weather forced the team into blanking off the ejector holes and so DRD was never actually used. However it did afford us the opportunity to see their version....
As we can see from the image above the Mercedes variant has their Airbox ducts slightly further back which allows them to be fitted with the engine cover. (Rather than be part of the Airbox structure and un-removable if the system isn't used, as we saw Kimi with the taped up over the Hockenheim and German GP weekends when not in use)
The arrangement at the rear of the car is very similar to that shown on the Lotus however one thing is yet unknown due to the weather not allowing the 'Device' to be tested. We can see in the picture above and below that the Periscope doesn't extend to the underside of the Rear Wing Mainplane. It may be the case that Mercedes simply ran their usual Rear Wing configuration and didn't bolt on the Deeper/Higher AoA Wing they could use in conjunction with the DRD. The other plausible reason is that it is infact designed this way and Mercedes plan to attempt blowing a larger section of the Rear Wing to gain downforce / reduce drag.
I see absolutely no reason as to why Mercedes can't continue to use DDRS in conjunction with DRD as one will not impact the other even in terms of packaging. As we can see below the twin pipes leaving the beam wing going through the chassis don't intefere with the placement of the Exhaust / Monkey Seat arrangement.
If you wish to understand my interpretation of the DDRS system that Mercedes use it is included in my recent Mercedes article: http://somersf1.blogspot.co.uk/2012/08/the-trouble-at-mercedes.html
In terms of others copying the Lotus design, as we have already seen Mercedes a team that is known for taking a long time to implement upgrades take up DRD I see no reason why others won't do the same. One crucial factor however is that both Lotus and Mercedes run fairly aero neutral exhaust designs. Whether this will factor in the design of everyone elses DRD is something I very much look forward to. As I have previously alluded to Mercedes and Lotus (nee Renault) have good experience with Passive devices but I see no reason for the likes of McLaren and Ferrari to adopt the designs too. http://somersf1.blogspot.co.uk/2012/08/bank-holiday-monday-musings-rear-wing.html
EDIT: Additional Images of Mercedes DRD from the Young Drivers Test 10-12th September
Images used in this Article are copyright their respective owners: Mario Keszeli / Sutton Images / Xpb Images