I use both the BT500, for travel, and the Logitech MX900, when at home.
Both pair-up well with the Sony BT Dongle. The BT500 works well, but is very small. It is only something like 3 inches long, and is very light. It is very responsive, and great for travel, but too diminutive for everyday use.
If you do a search, there are a couple of reviews on it.
The Logitech MX900 is great as well. Although I do not use it for gaming, I do not notice any difference between my MX700 RF mouse.