If we were in the Leon area we would probably back-track a bit to Irapuato to pick up 90 and then 110 down through Penjamo, La Piedad, Yurecuaro to 15D. We have taken this route several times from the Guanajuato area and the roads are all newly paved and widened with rings around the towns - another where maps are probably not up to date yet as the rings are very new. I do think the rings are on our Garmin now with recent updates. Anyway, this route and the other I tried to explain will completely avoid Guad and has very few tolls. Very little traffic holdups could mean faster times.
The latest maps are the SCT maps which are the gov't maps that Guia Roji gets their maps from. They only show major roads and minimal detail - but they are better and more detailed than Guia Roji. They are free to download online from SCT. . . . http://www.sct.gob.mx/informacion-general/planeacion/cartografia/productos-cartograficos/atlas-por-entidad-federativa/listado-de-atlas . . . but none of these maps will give you the kind of detail you get with Garmin or S&T - I like details. I checked my SCT map to see the road between Rio Verde and Cd. Valles and it shows 70 - no new road. The SCT maps were last updated in 2012 so I am not sure other maps will show newer roads. Depends on where they get their maps from. Unfortunately, Microsoft has discontinued S&T with 2013 being the last update so no more new roads will be on S&T. The latest Garmin updates do show roads no on either SCT or S&T. Unfortunately, Garmin updates can take many hours to download.
Some of my maps showing parts of routes I mention can be found on our blog at these web addresses . . .
http://www.briansue2.blogspot.com/2013_01_01_archive.html
http://www.briansue2.blogspot.com/2014/01/day-trips-from-roca-azul.html