Good post, but for anyone considering solo mining. If you are solo mining with a low hash rate (just a few GPUs or CPUs) it will be a long wait in between blocks on average. This doesn't mean you shouldn't do it–I have been a Monero solo miner for two years and an enthusiastic supporter of solo mining as better for the network and often better for the miner–but you need to be prepared for these waits and the inherent luck factor.
If you have enough of a hash rate to get blocks reasonable often when solo mining, then it is a no brainer, IMO. You not only help the network, and come out ahead in terms of less less risk of being ripped off by a dishonest pool, but you also gain from lower transactions fees since you wont be receiving a lot of small pool payments.
What's a decent hash rate to consider solo mining? I currently have about 50 cores producing anywhere between 1.5-2.2KH/s
At the current hash rate It takes (very roughly) about 100 kh/s to consistently mine one block per day. From there you can easily work out that that it takes about 14 kh/s to mine one block a week and 3 kh/s to mine one block a month. Each interval can stretch out due to luck to about 5x the average (very occasionally longer) or of course you can mine multiple blocks in that time period if you get lucky.
Alternately, at any hash rate, it could all be about fun or supporting the network, or because as other comments pointed out, even pool mining will only give you tiny payouts anyway, which are also less efficient to use (due to high transaction fees when spending coins received as many small payments)
With very low hashrate that's all about fun indeed, even pool mining because it can't make reasonable money for you.
Good point.