I was told by the Enphase people that they intentionally have more panels with smaller inverters because the generation on a daily basis is a bell curve with a flat top. The total power generated is the area under the curve. The claim is that the total area is greater with more panels with a "flat top" than if you purchased fewer panels with inverters that could handle the maximum output of the panels. Just looking at rated capacity of the panels assumes that you are comparing the maximum power output of the panels without regard as to how the power ramps up and down over the course of a day. With a few more panels the power generated at ramp up comes on more quickly than fewer panels and the same with ramp down. Thus, the area on the sides of the bell curve before "flat top" is reached is greater than the amount lost at the peak.
We have Enphase inverters rather than a central inverter and they have been trouble free for over three years now. However, our array is not subjected to the extreme heat of the desert. We are at 6,700 ft. so they are relatively cool by comparison and we have less atmospheric shading. Having said that, there are a couple of good reasons to consider a centralized inverter. First is that the centralized inverter does not need to be mounted on the roof and can be cooler. This of course just depends on your climate. Second, if you ever plan on having a battery back up and going off grid, then a central inverter may be better. The reason is that when you use a battery back up, the power needs to be reverse inverted from DC back to AC. With many micro inverters this would require and additional inverter to get the power back to AC.
To further make the decision difficult, there are many reasons to go with micro-inverters and you are probably already aware of them. They do lend themselves to additional panels down the road. They function independently so if one fails the entire system doesn't fail as opposed to the central inverter. However, one caveat is that, at least in our local, the utility will not allow any more than 20% of your main electrical panel capacity to be solar. Thus, if you have 200A service to your house, then the maximum solar would 40A, thus depending on your initial installation, adding more panels later may be a moot point.
Finally, welcome to the club. We have been totally pleased with our decision.
Reserved 4/20/10, Ocean Blue Ordered SL 9/30/10, ESVE Installed 11/22/10, Delivered March 8th, 2011.