I have a 5.1 system consisting of the BG Z7 towers, Z5 center, and r18i surrounds (don't have a BG sub, using an Onix) and the sound is spectacular!! The BG ribbon drivers offer great clarity and speed, and the speakers themselves are very well made (my Z7 towers are in real cherry veneers on ALL sides, and the center is black ash on all sides, very nice). These can be tough to find, and I bought them for far less than retail through a local distributor where my father's custom electronics / low voltage company has an account. They are well worth the modest (I believe) retail price tag!!!
BG designs and makes its own drivers, and many other companies use BG parts, especially the ribbons, which are very popular in the DIY market.