I don't think there's any reason to use Pro Seal. I do place a dot of Torque stripe on things I like to keep an eye on, assuming you can shine a light and find it in a mirror....gives me that warm/fuzzy feeling.
Del-seals and Fuel Lube and all that won't fix a poorly made flange. I like the del seals for some applications though, same as I like Fuel Lube. Aluminum anodized AN fittings, are designed to be torqued, not over tightened. Where I've found leaks, on excessively tightened fittings, I generally always do the same thing...re-make a new tube, replace the flange side fittings, use a Del seal and re-torgque and keep an eye on things. seems to work pretty well for me.
I've never had some of the more sophisticated flaring mechanisms, but the Parker tool has worked well for decades for me....I think you could over-kill things if you like...but it's up to the builder.
I don't see the benefit of PRC on that fitting.
Steve