I bought 3 R600s off eBay for a house the same size, and ended up reselling 2 of them because one R600 up in the ceiling covered the entire house. 2nd hand prices of Ruckus stuff is cheap enough that I wouldn't consider ubiquiti. The R600 is a great choice: it's plenty fast, has good range and is considerably smaller than, for example, the R610 or R710.