@sempracurtir
1 - See 2.
2 - Some 37x0's suffer inaccuracy after conversion, but they do regain accuracy if re-converted back to 37x0. The following thread is linked in Post #1 here too, you should read it: [Only registered and activated users can see links. ]. Probably due to 2 or 3 different GPS receivers in 37x0, they maybe handle the 34 gps fw relatively better or worse.
3 - Maybe personal likes/dislikes come into this and opinions vary. Most ppl refer the 34 menus and extra features such as Dashboards, Exit Services, Android Smartphone Link. Also you can enable mp3 and video players with 34, can't in 37.