Actually, the version of Irish that is taught in schools today is not a "version" of Irish as spoken in the 19th century, it is the exact same.
There are still the four dialects according to the provinces, Ulster, Munster, Leinster, and Connaught.
Apart from the pronunciation, (IMHO people from rural Connaught are the most difficult to understand), the most obvious differences in the dialects is that certain words and phrases have different meanings.

True, they have been standardised somewhat, yet the language itself remains the same as the 19th century version.