For a FB Elite+ traveller, there are no benefits at all.

At the beginning, if found this product interesting, but having had some night flights strapped on those punishing seats, I strongly suggest to buy only an eco one (in fact, it is better for sleeping, you are maybe cramped, but your back is not aching), the price difference is very important, or to use another company.

PV is often fully booked, indeed, but remember there are very few seats.

One more point : I saw twice pax upgraded from Eco to Biz and walking up the aisle a carry on in tow, on a night flight, my being in PV, and it is very frustrating.

For a day flight, PV is a good product, but avoid it during the night.

I cannot imagine AF changing these seats before 2020, even if competition is suppressing shell seats on eco+, because AF is very slow at accepting the idea they made a mistake.