Very expensive and not far better than the 200 Adapter

I have installed this 1200s-starter three days ago in our family house (built in 2000/2002). So far I had only 200 adapter from Devolo in operation. So I reached on the critical path from the EC to the upper floor and 71 Mbps on the ground floor in the living room 173 mbps. I then installed the 1200s adapter and upstairs the 1200s-WiFi adapter to the router on the ground floor. The sobering result: the upper floor, I now "stunning" 96 Mbps and 200 old adapter in the living room now only 160 Mbps. In particular, the miserable 96 MBps between the two 1200 adapters on the way between ground and first floor I think, given the very high price of the 1200 adapter more than devastating. I wonder if I should wait for an increase in the data transfer rate through firmware adjustments / hope or whether I again let go back the new adapter and it should perhaps even try to clearly better 650 adapters. The trend I am inclined to the latter. The wireless Access Point function of the 1200s-WiFi adapter works equally properly. At least something positive. Meanwhile, I also had to very fast support from Devolo contact. Previously, there was but one indication of interference sources in the net but no useful idea. These sources of interference but would then already the 200 adapter had to fight. I'm going to test the 1200 adapter for the weekend. However, I'm not much hope. Probably I'll send back the 1200s and give the much more favorable 650ern another chance.
Addendum 04.07.2015: I have sent for contact with the Devolo support on request the adapter connection data of the Cockpit software to Devolo and was hoping to get even more support for an improvement of the transmission rate. After a week of waiting, I have but then given up hope and the adapter can easily give back thanks to the Amazon 30-day Rückgabegaratie again. Now I'm going to try the 650 adapter. If they're no better than the 200, I will content myself with the 200 series. The 1200 adapter were absolutely not worth it for my situation compared with the 200s their money.