I am also considering buying it from eBay... I am with AT&T so it is GSM network (?) so do you think it'll be compatible with international models? I thought only people on Sprint / Verizon have issues because of CDMA networks... Why Samsung Pay won't work?
I think it depends on the phone's FW region code, not the radio bands. I would check XDA site for details.
Also, I don't think the Exynos has FM radio, but I doubt you care about that.