I have an 185mm that is one of my top 2 knives used.
nikiri is not a used knife in sushi. i find little to no use for it anymore. but in a french kitchen it kills veg prep! I will ruin a stock pot full of mire poix will a nikiri!
"A recipe has no soul. You as the cook must bring soul to the recipe." -Thomas Keller
165 has seemed short to me. In a strange way, a slightly longer (180ish) nakiri seems plenty long. I also seem to prefer a taller blade. I don't have space issues in my kitchen, and generally use a 15x20 board.
The finest nakiri I ever used was one by Butch that was roughly 170, with a tall heel and slightly shorter toe. It also had a rounded tip, which I liked because I've used some that love to find their tips jammed into the board when chopping double time.
For what its worth, most of my knives are 210 to 240 but I have a 165 nakiri (moritaka) and its a great size and I never feel like I wish it were longer. There are many shapes of nakiri but mine looks like a dollar bill on a stick with a 90 degree heel and tip. Best push cutter I have, plus it allows me to make vertical and lateral cuts without having to raise the handle up like on the nakiris that have a rounded tip.
One thing you can give and still keep...is your word.