Another kit to look at is the various Exodus audio kits (61,261,LCT,2641 etc).
I've heard both: my take?
1) The GR AV3 is smoother and warmer sounding to me. It is also more efficent (2-3 db) and probably an easier load for a receiver amp. The GR is probably easier to listen to with typical "mid-fi" sources (mainstream CD/DVD) as it has a very forgiving sound. Cheaper by a fair margin also.
2) The Exodus audio offerings have far greater bass extension, and could really be used without subs in many applications. They also have far greater power handling capapbility and will probably show of higher end equipment better than the GR, particularly if you're a fan of that "etched, I need to hear *everything*" sound. Tese speaker will expose every nuance, bad or good, of your audio setup.
In the end, you need to look at what kind of sound you like, and what equipment you have. If you have mid-range equipment, an ear that likes a mellower warmer sound, and a sub to fill in the bottom end for movies or audio with deeper bass, I'd go with the GR speakers. If you have a big ballsey amp, love a speaker with legs that go for miles, and have aspirations for very expensive equipment and the best recordings, go with the Exodus /Audio speakers.
One last comment... by the words i wrote about these speakers sounding better with mid-fi or high end euqipment, I DO NOT mean that they will only sound good with those components. The GR speakers will sound great with high end stuff, the exodus audio ones will likewise sound pretty good with lowend sources. BUT, they both do have distinctive sounds, and to my ear the GR is easier to listen to for long periods. The Exodus speakers to have a certain *wow* to their ability to expose music though.