Maybe this happens in other districts, but in ours the ratio is the same in all the schools whether they are title 1 or not. Or at least they say they are trying to keep it the same. The only difference that I really see is the intervention programs for reading/math. DD has 26 kids in her third grade class and no aide. Last year in second it was the same number. Some of the best performing schools actually have a lower ratio just because they are small schools and some grades hardly have any kids. So there might be one third grade class in the school with only 16 kids in the class. DS started the year at DD's school and had 23 kids in his first grade class (no aide). He switched to a non-title school and has 22. And for whatever reason the new teacher seems to have a lot more time to spend with him, so he's doing better in the non-title school.
I suppose the devil is in the implementation. Typically, there are more aides in classes with special needs kids, who are theoretically available to help with all the kids. If nothing else, the ratio of kids to adults tend to be lower, which may also help with maintaining control in the classroom if that were an issue.
