It definitely sounds like it’s worth going for, the current model class that I’m working on is already 1,231 and is not yet finished, with the rest of the functionality and more validation (I know it’s not got enough validation yet), I wouldn’t be surprised if it ends up being 5,000+ lines long without using the data mapper pattern.
Long term i might also extend PDO to put wrappers around CRUD, which would make it easier to work with especially for things like IN clauses with prepared statements, as I’d just need to send over an array with the values and the sql statement to be prepared