Got my G3 about 3 weeks ago and it is sweet. Changing/cleaning filter media has never been easier. I know alot of people seem to be down on the G3 because it costs almost as much as the G6, but I'm glad I went with the G3. I have a 45g cube (24x24x18) and I also have a Fluval U2 running as a backup, and even with the spraybars attached I had to run the G3 at about 70%.
This past weekend I was playing around with the fittings it came with (modular loc-line style fittings are awesome!) and I ended up popping the solid ends off the spraybars and snapping on the stock return jets to the ends. This allowed me to run the filter at 100% strength and now I have the spraybars in the back corner at a 90 degree angle aimed slightly upwards creating a nice "mini-vortex" to eliminate surface scum, while the ends of the spraybars emit a gentle downward flow throughout the rest of the tank. I'm seriously considering removing the U2, but it's always nice to have a backup just in case.
The chemical media container on the G3 is just the right size for my system, I have it filled with Fluval peat granules (My previous filter was an AC70 HOB and the peat I had in that filled the G3 media container perfectly). I also just picked up the fine prefilter cartridge last week because I was doing a major "trim/rescape session" and ran it for the next day afterwords and it made the tank super clear. It does clog up quicker obviously, so I'm only gonna use it when I need to and run the stock prefilter the majority of the time.
I might post a pic or two some day if I'm motivated.