Except if you live in a Japanese apartment I don't see the point of going to micro. You will pay for the size you win in Fan speeds and noise, not to mention the future upgrades that can turn into a headache. Its not my conception of rock solid in any case (no pun intended).
When I built my wife's work computer, I went micro ATX put into a standard ATX spec "mini tower" because it was the least expensive "quality" mobo that had all the features I wanted. It had the right video, audio, network, etc. options that I required, but was $30 cheaper than the equivalent full ATX mobo. The micro ATX board has one full speed PCI-E slot for vid card, and 2 other slots for any potential necessary upgrades, has 6 SATA slots, 1 floppy, 1 IDE, and all the usual other onboard connectors. It's almost as full featured as any other normal ATX board including all back panel connectors, but at a much smaller size and lower price. It fit all my components without any problem and although the onboard connectors are closer together and therefore a bit harder to work with, the mini tower case is big enough for a full ATX mobo so installing it was actually very easy.
So there are lots of reasons to go micro ATX even when not trying to cram it into a tiny case. In my situation, I could have put almost any normal mobo into the new computer case and I chose a micro ATX mobo because it had 100% of my required features at a lower price than an equivalent quality full ATX mobo.
Plus... Sometimes people need business-class TPM modules on their mobos, and I've found these to be much more common on micro ATX boards. I didn't need TPM but if I had, it would have been easier/cheaper to get it on a micro ATX mobo.