They're not the same. There are far more of them on the 777s and the 'please stand back behind the yellow line' external announcement is so loud I can hear it from my house with the windows closed despite living several streets back from the railway.Aren't the announcements the same as on the old trains... not noticed them being excessive.
It's only a 15 minute wait as long as the next one turns up, which it often doesn't!