I also got a system through energy matters. 5Kw Aurora inverter, with REC panels, i ended up getting 2 extra panels, so total 'input' is around 5.3kW or so.  I did this after reading plenty on whirlpool forums about boosting panel numbers a bit - some guys are putting 6kW into 5kW inverters - and these are guys who are sparkies that install and design a lot of systems, so i'm assuming they know a lot more than me!

Very happy with it, haven't had an electricity bill since installation and have a few hundred credit. I estimated the system would pay for itself in 4 years, and it seems to be on track.  The biggest thing i think is making sure your panel orientation is correct. Our neighbours got some poor advice (isntallers wanted the easy option), and they have the exact same system as us and produce 30% less power due to western rather than northern facing panels.  I also et up and clean them every month or two with a hose to keep the dust down during dry weather.