[Q] Is the Z2 still a solid buy?

Hey guys,

I'm thinking about getting a Z2 because they are pretty cheap now and I don't really see such a big benefit when looking at the Z3 or Z5.
I'm coming from a Nexus5 on which I stupidly broke the screen so I'm in need of something new.
I do however have a few worries about getting the Z2 maybe you can help me out.
1. Does unlocking and flashing custom roms break anything? I love custom roms or pure android so I really want to use it however I read somewhere that flashing custom roms loses some features on the z2. Does it worsen the camera due to drm not working?
2. Android M support was announced by sony however how long does it usually take them to roll out updates?
3. Does the Z2 have the same "screen cracking without force" issue as the Z3 seems to be plagued by?
4. Are there any really compelling reasons to get a Z3 instead of Z2? I read some reviews saying the screen is better but thats about it...

Thanks a lot.