First: I am longtime DLAN users. It all started with 6 MBit devolo adapters of which (3 MBit DSL) were sufficient for those internet speed. But when 25 Mbit was available, I needed new adapter. I chose 200 Mbit adapters from Netgear. However, this brought less than half of Internet speed (about 10 Mbps) up to my room. So I was excited to see what the devolo have so on it. As part of Cyber Monday week I ordered the 200 and the 500 series. Even the 200 series with 24 MBit brought to almost the entire speed. Reason for the increased output is the integrated filtered power socket, the Netgear adapter did not possess. However, when I tested the 500 and this was with 27 MBit just 3 Mbit fast, I was a bit disappointed, we would still have reserves for possible increases. The speed relate to the longest to be bridged with me link.
In conclusion, one can say that the transition from DLAN without filter outlet brings a lot, mainly because one has usually plugged the power strip with computer, monitor, speakers and light next to the adapter and this considerably slows down the transfer. You have to transmit relatively long distances, you should not hope on 500 large speed improvements when switching from 200.