Think of one full charge, 13.8 kW, as one gal of gas (each generally provides energy for the same driving distance). How much is electricity in your area year round? What is the cost of a full charge? How much does this “gallon” of electricity save over a gal of gas? How many miles/year would you drive on battery? What is the potential cost savings/yr assuming 34 mi/charge = 1 gal gas? Lots of variables that only you can answer. May be really tough to justify that extra cost without the former rebate. And might take many, many years to break even, when you may no longer even have the car.
The car itself is virtually the same as the HEV. EXCEPT, there is no spare tire or even a jack (nor is there even room for one) and you lose the ability to lower the cargo floor several inches for extra space. The HEV also gets about 10% better gas mileage on the highway/long trips (much less weight!) - expect the PHEV to get 30 mpg-ish on the highway, assuming you drive over 70 mph. Cold weather will also reduce your electric driving range and mpg average by 10-20%.
In return, you get slightly more power (about .1-.2 sec. faster 0-60 mph), slightly better handling in the corners (battery weight lowers center of gravity) and its obviously quieter when driving on battery. And of course, less trips to the smelly gas station, but you will constantly be fumbling around with plugging/unplugging your car every day.
The hilly terrain/regen braking is a moot issue. They are both the exact same, in that respect.
So unless its a real cost savings benefit for your individual gas and electricity cost situation, the PHEV is most probably not worth it over the HEV…$6K extra upfront (don’t forget extra interest if financing) is a big sunk cost, although may get some of that back on a future trade-in/resale.