Parang mas safest si factory unlock ata ka phc when it comes to updating ios version compared sa gpp unlock at semi-factory unlock, pwera lang kung my hardware problem siya sa cp example hardware aspect sa signal niya po.,,
iOS 12 is better than iOS 11. Experience ko sa mga iphone, the more na iupdate, the more na bumabagal sya. I have 4s back then, sobrang smooth nung ios5 and ios 6 pa lang sya, pero nung nagupdate ng ios 7, 8, specially 9, almost unusable na yung phone. Same goes sa iphone 5. Ios 6 nagstart yun. Super smooth. Okay pa rin naman performance nya hangggang ios 10. Meron din ako dito 5s, isang ios 12, isang ios 9, honestly mas smooth pa ang ios 9 sa ios 12.
Opinyon ko lang, do not update your iphone for more than 2 years from its release date.