500pf vs 500 f4/g

[KCPhoto]

I am going to begin squirreling away some acorns for a decent prime super-zoom. As much as I would like to go for a 600mm, I simply can't justify it. Even though we all know we can blame Steve when we are called to the carpet by the At Home CFO, the jump is significant. There is a very good condition 600 g version for sale locally by a great guy that has shoulder issues. I wish I could justify, but simply can not. I have a 200-500 and I likely will not sell for times when I think the zoom would be better to carry.

Ignoring considerations like weight/handhold-ability, physical size, ease of hiking, etc, and given that you can pick up a used f/4 g for generally similar pricing to a new pf; what are thoughts from those who have owned both?

1. The extra stop of light leading to the ability to run 1.4tc with decent success on the f/4 seems valuable, but does it cancel out any of the (ignores) from above?
2. Image output. As image quality is VERY hard to define due to subjectiveness, given you could capture the exact same spot in time and light, does the f/4 offer a noticeable jump anywhere.
3. Weatherabiltiy and overall ruggedness
4. Hard light situations like strong backlighting, sun, or another bright source in the frame, maybe even looking for an intentional flare.

Yes, I know I need to rent and/or borrow both prior to purchasing. Renting the 500 g is quite pricy and almost seems counterintuitive to the saving up process, but I know it is probably smart. Any other considerations welcome and encouraged for me to consider as I go through this process.

 

[FB101]

So, ignoring considerations like weight/handhold-ability, physical size, ease of hiking, etc... therefore ignoring the very reasons why the PF was added to Nikon's line is the f:4 better? Yes indeed. I don't own the f;4 but I've rented it many times, and here is what I experienced:

1. utilizing a x1.4 multiplier is one of the key reasons why you'd pick the f:4 lens over the PF. Another way though to get there (for many of us where cost and weight do come into the decision set), a D500 + PF or D850 + 500pf "reaches" about the same as a D5+500 f:4 + x1.4 ( if you take pixel density into consideration). For me, the biggest gain is that I now carry the D500 with 500pf on every walk I take - 99% of the time I don't see anything worth shooting but I never hesitate to grab it even if I know i'll be out for a few hours, which I wouldn't do otherwise. I know you said "besides weight" but honestly that the whole reason for the PF.
2. Yes the f:4 is slightly better - I don't see it in sharpness but backgrounds and OOF transition are smoother on the f:4 - not as good as the 400 f:2.8 but better than the 500pf
3. the f:4 feels a bit more rugged but I am not sure that's anything besides feeling the heavier weight. For sure the f:4 has been around longer and they age very well so far. Time will tell on the PF
4. I had all sort of issues with the Canon 400DO when I used to shoot Canon but honestly this PF is mostly free and clear of issues so far. I tried to get it to misbehave when I got it and I really couldn't make anything ugly happen. That said, it's been pretty grey and cloudy here so I've not pushed it very hard yet.