I would seriously reconsider taking something like a 7D to Mexico in the current climes. Unless you are going about with close protection then you are quite simply opening yourself up for a whole lot of trouble.
I would look at taking a more discreet compact with me.
I haven't been to Mexico recently but am aware of a group last week robbed at gunpoint and everything stolen on the Guatamala / Mexico border.
Perhaps though, someone else here can give you a more personal opinion of travelling there with tog gear as this current time.
Please have a look here
http://www.fco.gov.uk/en/travel-and-living-abroad/travel-advice-by-country/north-central-america/mexico1 for the latest travel advice.