Tanguay should be used with the caveat that there are errors, particularly in how he writes names, he ''standardized'' them to his own era's usage. 19th century. But in certain areas his work is the only source available, since he had access to records earlier than most everybody else who undertook similar work. Many of the records he was able to consult were destroyed/lost before the next guy came along.
Also, Tanguay often will try to make people fit in with existing families, when they were in fact immigrants or were unrelated. This doesn't happen too much, but it does happen.
So, with that said, yes, use him by all means, but remember his limitations, and whenever possible supply more primary sources for your data. René Jetté's work in some instances actually just repeats Tanguay, but it is not always apparent that this was what he did.