To "charlatan1978": I knew that L920 wasn't on the current list of eligible phones to get W10M, however I didn't know if there was an update concerning that list. So i stayed with my current version (which is WP8.1 Preview for Developers) because I'd heard about a lot of bugs in insider builds so I didn't wanna experience such lags and crashes.
To "N_LaRue": I knew about the 950 & 950XL carrying the official version of W10M but I was wondering about it's release to all other phones. My L920 has O2 as a carrier (although i bought it from Greece), I don't know if that's gonna be a problem. I've thought about enrolling into the Insider program, but I've been hesitant up until now because of the bugs and crashes reported.