Hi
I have converted a couple of people to Nightly, both at MozFest last year.
The first was a fellow volunteer after a pre-event briefing session sat outside a nice pub in Southwark. (The beer was okay, but was subject to the Southwark beer price multiplier…). We were having a general conversation about Mozilla, and I mentioned that i had side loaded Android Nightly onto my phone. They had not realised that there was a Nightly variant of Fennec available, and has since installed (and enjoys using) Nightly on their phone.
The second was a visitor to MozFest. I had explained the cool “make a desktop from the Nightly page” activity, and they were keen to try. I took the opportunity to explain how useful Nightly is to Mozilla and how it enables people to see features before anyone else. They sounded impressed!
I would never look for force Nightly on anyone, and it would be wrong to completely downplay the sometimes interesting user experience, but there are lots of positives to getting knowledgeable users on the Nightly platform.