Nib preparation mileage and preferences varies! From your post, it is clear that you have done some research on this -- good!
For what it's worth, I'll throw in my personal experience. I've tried many, many methods, except that potato thing. And what I kept coming up with was, regardless of the method, it just took me lots and lots of rubbing before that darn nib would be clean enough to properly accept the ink. Frustrating! I'd been hopeful to find somebody else's magic method that would work ... because it was irritating to me that it took so long to prepare a new nib.
I should mention that besides the potato thing, I was extremely chary to use the flame method, even though Michael Sull recommended it. I was so worried that I'd ruin the metal in the nib that I just didn't want to risk it. But finally I did, and for me, this has got to be the most "magic" method I'd ever tried! I'm still extremely cautious, and sometimes I'll need to take several passes, waiting in between for the thing to cool off. But, wow -- nib preparation in seconds!
I might also mention that when not using a previously prepped nib for several weeks, sometimes it requires prepping again a bit the next time I use it. Not sure why, but might be good to know.
Finally, the flame method opened up opportunity for me to get this little alcohol lamp which doubles for melting sealing was. And because, cute.