Surprised the auto-dimming mirror was deleted from the 2017 SV. Oh well, the stock Nissan auto-dimming mirror not all that great anyway:
I recently upgraded our 2016 SV's form the stock Nissan "Auto-Dimming" mirror to a much better grade of Gentex mirror (I believe Nissan sourced Gentex for their mirrors, but had some features deleted to keep costs down).
The new mirror features a frameless design that is less bulky/distracting during the day, and the HomeLink buttons are softly illuminated at night. As well, the auto-dimming feature is much improved over the mirrors our SV's came with (sometimes I wondered if the Nissan mirror was even working as headlights were glaring at me - it took several cars worth of headlights to trigger the stock mirror).
One thing to keep in mind is if you park your car outside your house or garage... if your HomeLink mirror receives power even while the car is off, you have a security risk. Someone could break into your car (or even reach in if the window is down) and open your garage door with the push of a button.
For that reason, I have intentionally wired my new mirror ONLY to switched power. The HomeLink buttons only work when the car is turned on. The mirror still remembers the learned remote codes even without power, so all works as expected. I especially like that I don't have to hold the button down to activate the door; the mirror not only has a long range, but keeps transmitting the code for a bit after releasing the button.
The only downside to the frameless Gentex mirror is the "upside down" shape compared to the LEAF's rear window. I'm the kind of person to notice that detail, so simple solution was to twist the mirror upside down with the HomeLink buttons on top. Now it nicely matches the rear window shape, and looks even a bit cleaner.
Here's the mirror I went with: