I'm with Axo here, and lets not forget another important thing for the fellow from Edmonton, of having a good sense of observation, situational awareness, and good old common sense for getting a feel for an environment.
Its hard for someone who has never been to Latin America to assess stuff at first--the language is foreign, everything is different, its hard to evaluate what is dangerous and what is not....I realize this, but at least reading as many trip journals from bike tourists will give you some good basis of stuff and experiences, and will help you pick up what to expect and what to see and experience.
before the internet, we just winged it travelling in latin america, and learned on the fly---that said, you still have to not be clueless, but then this touches on personal responsibility and ability to look and learn , and to be able to deal with travelling in other cultures, you cant just learn it all by surfing the net.
Edmonton guy--we dont knwo if you will ever really do this trip, but it is doable, and being informed as much as you can for routes etc will help a lot.
I also suggest becoming as knowledgeable hands on wise of taking care of your bike and fixing stuff, know your bike inside and out, and be confident that you can deal with stuff--added bonus is that by knwing your bike well mechanically, it drastically improves the chance of NOT having mechanicals, and knowing the signs of small clues of stuff to deal with before they become bigger.
Oh this trip is a 100% go....barring anything serious happening. As for the negativity... Yeah, I've had sooo many people warn me that I'll get robbed or kidnapped or even killed in Mexico or Latin America. I'm more afraid of going through the US, truth be known. And yes, I'm very mechanically inclined. And yes, I am taking Spanish lessons with a tutor here in town. I've also read probably every Journal on CGOAB of people touring through Mexico. So I'm ready...