Personally I do somewhat prefer solo...It is nice to ride with a group of friends, but too often than not you end up with people who want to ride at different times, at different speeds, etc, etc.
That said, you do need to remember you are less visible to others when you are out alone vs in a group, and also if you go down, there could likely be no one nearby to assist or even notice that you went down at all. I think the article does a good job though regarding letting someone know you are out, rough route, and when you should be back (in case you aren't), as well as bringing a cell phone, credit cards, etc. CAA Plus is also good in case you have a breakdown, and a battery pack isn't a bad idea in case you somehow end up with a dead phone battery.
As for mechanical breakdowns though...is that really something many worry about? Maybe it is just because I have modern vehicles, but that never really crosses my mind much, besides maybe a blowout if I hit a nail or something. Most modern bikes should be as reliable as most modern cars...