It's not all that bad Inspecter V. I say go for it.
I know a few people who ride through Mexico frequently and have no complaints. One of them makes two trips a year: 1 to Baja and 1 all the way down to Cabo. Yes, there are some gnarly roads, etc. but nothing that can't be managed with a little care. Unleaded gas is available (Pemex stations) and should run fine for you.
Check out the Questions section on this site:
www.eldiablorun.com. I'm betting it'll answer a lot of your questions.