Man I tried so hard to level Florina into a decent character, and it never happened. Dropped her for Heath later on, now that guy was a real hard ass.
Yeah prepromos tend to worse statistically than if you manually promote your units. Prepromos are more for those who need units since all their early game characters died.
You can do it. If you put in effort, she becomes a great hit and run mage killer(she's still great for other stuff too) Probably not as good as heath or the triangle sisters from Hector's Story tho.
I just love to have as many high mobility units as possible because that's kinda the main basis of my playstyle.