Yes there is a measurable advantage to MPPT over PWM. There is no simple answer on how big the advantage is - it is highly dependent on the specifics of your panels, the environment your usage and batteries. The range is around 10 - 35% more power from MPPT over PWM.
The explanation is complicated. With a PWM charge controller, the battery sets the voltage and you get what every current your panel can provide. So in the example we discussed earlier of two panels with a 15A Imp and Vmp of 21V, under ideal circumstances you will get 15A * 14V = 210W through a PWM controller. With MPPT, the panel voltage is decoupled from the battery voltage and the controller will try and find the combination of Amp and Volts where the panel produces the most power, called the Maximum Power Point Tracking (thus MPPT). In the above example an MPPT could run the panel at 15A and 21V (315W) which it would convert to 22.5A at 14V for the battery. This example is under 'ideal conditions' and in the real world it neither the total power, or the difference will be that high.
In your case, where you are willing (excited?) to upgrade and do the work, an upgrade to a Victron MPPT controller would be worth it.
For Brad, who would prefer to use his existing equipment, chances are he doesn't need to upgrade. On that front, I did find the manual for the current ZAMP 30A, and the only difference between the LiFePO4 setting and AGM setting is the float voltage (13.4V vs 13.6V). Assuming to older ZAMP has the same AGM settings as the new one, then there is really no significant issue with using the AGM setting with LiFePO4. Lithium doesn't need to be float charged (hence the lower float voltage) so if you were to turn the solar charger off when the camper is not being used, the end result would be about the same.
