Personally I have found in my experience that every single NF is different from each other. ENFP is different than ENFJ is different than INFP is different than INFJ.
That said I have had a special connection with each one, finding I think alike and differently from all of them. The relationships with the least friction for me are ENFP/INFJ. This is why I find it surprising that some INFJs here don't get along with ENFPs. Of course everyone is different.
I personally don't believe there is any more connection because of the shared J or shared P as some have stated.
I find that at first, people notice the J and think they are similar. ENFJ and INFJ notice they are similar, just as ENFP and ENFJ notice they share the ENFJ. That said, I find that as the relationship deepens, ENFJ and INFJ notice a large difference in one another, as do ENFP and INFP. Not that this is necessarily a bad thing, but I think it comes up over time. The ENFJ/INFP and ENFP/INFJ relationship is more straightforward in regards to this. They are either going to love or hate each other pretty much right away from my experience, though I think as the relationship deepens they start to notice more and more unexpected similarities. This is a large generalization but certainly something I have noticed.
However, I am way off topic here, Smiffy, what do you think you are.
You mentioned:
no one is going to fit any one type perfectly. The human mind is too dynamic and adaptive. Everyone will have elements of other types available to them.
Cognitive function preference indicates how we reflexively think, not how well we can think, nor what we think about.
"I like this statement! nice and open ended!"
ENFP? Clearly you are very close to the J/P border, but if you HAD to choose, if this monkey was holding a gun to your head
(Ok, so it's a party confetti toy, but it does shoot) what would you choose.
You can say both if you want too, but most balanced people will fall to one side or the other. It will be very rare to be equally J/P just as it is very rare to be ambidextrous. Most people who claim ambidexterity are actually what is referred to as "mixed handedness" meaning some things with the left some things with the right. True ambidexterity is using both hands equally well at everything. In the same way, true J/P balance (or ENFX) means that you have to use both equally well and equal amount of the time. Of course, this has to be rare because it is only 1 point on the scale X is dead center and EVERYTHING left is P and EVERYTHING right is J. So J and P comprise much more than X as far as the MBTI system is concerned.
P----------X----------J
(BTW, X is not in actually MBTI theory, but it is becoming more accepted among MBTI proponents.)
Hopefully that all came out right (or is it left?).
