If you're doing mass updates or deletes, then an ORM is not typically going to help much. If you're grabbing a bunch of data, performing operations on each row, and writing it back to the db, an ORM can be a big time-saver.
I don't know how to explain it any simpler than I already have. You'd have to try it. If you feel like the setup for Rose is too much, you can try Class::DBI. It's not as capable as Rose::DB::Object, but I still use it, and it makes direct SQL very simple.
BTW, I usually avoid REPLACE. It's a slower way to do that operation than the alternatives and it makes DELETE triggers fire. If you're only supporting MySQL and you want to handle both cases with a single statement, INSERT...ON DUPLICATE KEY UPDATE is better.