luckylinux "beater" phone, something I don't treat with the utmost care. "Navi" - I use it for the maps on my bike (handlebars vibrate, I don't want OIS in my main phone to get destroyed).
I didn't go for refurbished, as I suggested it's not even my main phone. I got it exactly for the reason you consider yours: to try GOS. And I just got mine off eBay, from the random company.
...and you could probably sell yours once you decide to upgrade.
As I said, it's your decision. Sure I'd prefer 8 to be my main/permanent phone. Your mileage may vary.