Monique,
"I see Trenitalia actually has a 7,90 train option, but I’d like to get into Florence earlier and it’s over 3 hours versus 1.5 hours on ItaloTreno."
Could you clarify which train and date you're looking at that takes 3 hours from Rome to Florence? The Freccia trains take exactly the same time as the Italo trains, as they travel at the same speed on the same tracks. I have to wonder if the 3 hour train was an Intercity / Regionale, as the high speed travel time on that route is ~90 minutes. Also, which website are you using to research trains?
Using an arbitrary date of 27 July, Italo is showing fares a €9.90 PP in Smart category (some restrictions).