Is it safe to disable system google apps I am looking on to using some of the applications provided from the manufacturer and was wondering if it is safe to disable some google applications.

I am looking to disable: 


GMail (this is my biggest concern ATM)
Chrome
G+ (that annoying 'photos' app)
Play News, Music, Newsstand (I believe these are safe)


If you know any applications which are totally not safe (excluding the core ones, like Google Play Services, etc.)

My device is:

stock HTC One (M9)
 Android 5.0.2
Short Answer : Yes


  These are just apps and you can disable it.But, when the app(any app),
  for example the app need to update and you cannot update the app when it search for Google play(for example) to update and you
  need to new market for update the app.




also, as you said :


GMail (this is my biggest concern ATM) 
Chrome
Google + (that annoying 'photos' app)
Play News, Music, Newsstand


these are always safe to disable and if you don't using of them, you can disable it for reasons like, 

clear the ram and it means, the phone speed can up.!

good day.