I went through and verified all these routes by hand. I learned that where you sell an item, not where you buy it, is what matters. I also recorded how much XP I got, and discovered that earned XP is not clearly related to either item level or profit gained. There is something more at play here.
I would paste the data here, but I can't figure out how to make the forums display the table in a non-FUBAR fashion. For now, the data lives on the Talk page for the Trade Routes page on the wiki. You'll need to sign into the wiki using your forum credentials before you can see the page.
The numbers are all from an unbonused/grouped JE, so they are as raw as raw gets. I may have made a mistake or two on some of the path lengths, I'm still working on a script to double-check my eyeball work.
http://net-7.org/wiki/index.php?title=Talk%3ATrade_Routes#Confirmation_of_lvl_4_and_5_runs
TL;DR: FN->NV is NOT the best trade run (for credits or XP) if you are a PP. There is something better. 3 jumps better. Also, while the rule of thumb that greater gross profit = more trade XP, the rule is not linear. The XP per unit profit varies wildly, some other factors are at play.