I think MPPT becomes a more economical choice when you are putting together a larger system, say >500 watts. The MPPT controller costs more than a PWM, but the MPPT controller allows you to use high voltage panels which are usually much cheaper per watt than 12V nominal panels. So at some point you can justify the more expensive controller as the cost is offset by the savings in panel costs.
But in a small solar setup, I don't think the increased cost of an MPPT controller pans out. But it can squeeze more charging amps out of your panels during bulk charging.
2012 Aspen Trail 2710BH | 280 watts of solar on the roof | 2x6V GC batteries | 100% LED lighting | 1500 & 300 watt PSW inverters | so far strictly boondocking