Hi Joe,
I own the Persona 3F's and have listened to the Founder series. Without elaborating, the basic differences I noticed are that the Personas impress with their presence, uniform response, soundstage and imaging. But the Founders were close and also give you great bass integration and response with active room correction built in.
It also depends largely upon the rest of your system. But if you love your Prestige 75F, imo it's likely that the Founder 120H will work well for you. Any chance that you can audition these yourself?