@john2k 

Hey John

You are indeed correct, the TL-WPA7510   has  750mbps WiFi speeds and 1000mbps powerline speeds, bear in mind this is the theoretical max so your actual transfer rate will vary on distance, static, cable type etc etc.   I had the 1200 models and was averaging around 350mbps on the powerline connection, as an example.  If you get 200 at present, these should be the same.

Ok so the device also has a 1GB LAN port, this means your computer or whatever you have cabled into it will connect at 1000mbps, basically you wont be restricted in any way as this will be faster than your homeplugs/house wiring will ever really allow (~200mbps i believe you mentioned) 

The tl-pa4010 ones you had before came with 10/100 ports for some unknown reason!!  Therefore if you powerline connected at 200, you would be limited to 100 by the port which was usually the case with that older model.  This wont be the case with the WPA7510, your in house wiring will be the limits here.

Hope that helps!

Phil