Generally speaking, water bottle/filter combinations are not considered "high end" filtration units. For sure, because it's a filter, and not a purifier, it won't eliminate viruses. Need a purfier and/or chemical treatment to get viruses.
Which method you use depends in part on where and under what conditions in Mexico you'll be sourcing water, and how sure you want to be of using trouble-free water.
For what it's worth, I've been going to Mexico (Manzanillo, Colima) almost annually for over 20 years, two to six weeks at a time. Drink, and brush teeth with, bottled water only, but have washed dishes with tap water. And we eat with abandon in restaurants in some pretty out-of-the-way places. Neither me nor my wife have ever gotten Montezuma's Revenge (YMMV). For the record, neither of us has a drop of Hispanic blood, so if there's such a thing as genetic immunity, we don't have any.
Having said that, I'm not convinced that bottled water is necessarily better, at least here in the U.S. The Natural Resources Defense Council did a 4-year review/test. Conclusion: just because it's bottled is not an assurance it's any cleaner/safer than tap water.
Tequila and Sol beer have been problem-free too. <img src="/images/graemlins/grin.gif" alt="" />
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"Things that have never happened before happen all the time." — Scott Sagan, The Limits of Safety