If the gate staff are doing their job and checking ID's against the boarding passes then there should be no problem with self service.
I admit, I am biased because I do want to save jobs in my chosen industry. However, I do speak from experience when I say that a similar scheme in the 1960's ended in tears with the 1970 hijackings!!! I have to say BA does things "by the book" but some airlines and their handling agents actually "bully" their gate staff into getting "on time departures" which leads to slipshod practises (like not checking ID's as well as they might!!!)
Even at BA, we are put under a lot of pressure to get flights away on time - especially since this bluddy EU compensation ruling! I have been guilty on a few occasions of not checking ID and, let's face it, how often are you asked for an ID on a British Airways Domestic Service???