The Roji is fine for Mexico if you are going to be on well traveled cuota roads or if you are going to be on well traveled state roads. Remember, it has some real big errors if you are doing any serious riding.
A lot of tourists use the Roji, but there are other options that are better, the Roji is usually used because it is the easiest to buy and usually the only map of Mexico they have ever used, maybe apart from an AAA map.
Mapasindependencia are not too bad, even the Quimera is just as good as a Roji and a little cheaper.
You can download some very good aviation maps for free online. These cover a wide swath of Latin America and not just Mexico. They are large files, with a lot more accuracy than the Roji will ever dream of having.
Using the google maps etc... is ok, but like any other source, it won't give you an idea of the condition of the road which is very important. That you will get by simply asking locals.