Your views are opposite then Hanafi fiqh, I find it conflicting. Well if you say that to be on safe side then why we cannot start Fasting of Ramadan one day earlier TO BE ON SAFE SIDE
The Holy Prophet Sallallaho Alaihi Wasallam has stated the Allah has said that out of my servants I love those more who rush their Iftari and delay their Sehri [Ahmad, Tirmizi etc.]. It is also reported that Allah chooses those who hurry their Iftari and delay their Sehri [Tibrani]. Rule : To eat Sehri and to delay it is Sunnat, but to delay it so much that their is doubt that the dawn will break then this is Makrooh [Alamgiri, Bahar].
2:187. ................, and eat and drink until the whiteness of the day becomes distinct from the blackness of the night at dawn, then complete the fast till night, ...................... Thus does Allah make clear His communications for men that they may guard (against evil).
In most of the muslim Countries the FAJAR azan is actually 15 - 20 Min. before time. Also do you think that until one hundred years ago the Azan was on dot???? I don't think so. Still if you start listening to AZAN-e-Fajar it will continue in different masjids for at least 15 mins after first one. Which one will be right ( All of them ?????) and which one you will follow (GEO, PTV or local Masjid)
Isn't fajr time and dawn time totally different? In my namaz table, fajr namaz time is at 5:20, does it mean I should stop eating at 5:20am? But looking outside it is totally dark upto 6am and dawn is not until 6:15 am, does that mean you are still allowed to eat even after the azan? Or does it make the roza Makrooh?