Thanks to everyone for well thought out and articulated replies.
My previous company required all FMA changes to be verbalised including those generated automatically by the FMS, with no response from the PNF. On several occasions, I have seen pilots callout what they expected to see instead of the actual indications.
An example: after a pilot thought he pressed the APP button, he called, "Heading mode, loc and glide slope armed'. In actual fact, we were in LNAV and ALT HOLD.
My current company has a new type of aircraft and is not quite settled on the fine detail of its procedures yet. Currently, all FMA changes are called and the PNF responds with 'checked'. We also call the applicable speed limit prior to making a configuration change. This can also be error prone; a number of examples exist of pilots calling for configuration changes above the limit speed in spite of the verbalisation of the limit.
The intention of the callouts is clear; it keeps both pilots in the FMA loop and prevents over speeds. The paradox is that it can also degrade safety by creating a large amount of chatter during the busiest periods of ATC, particularly when pilots raise their voice so they can be heard over the radio! I don't particularly appreciate that, on a dark and stormy night, in a foreign country when I can barely understand the controller at the best of times.
In my previous job, a couple of pilots were exchanged with the parent company airline with a view to establishing interoperability of crews. The parent company procedures were basically silence unless something was wrong, whereas our procedures were to talk when everything was right. The pilots on exchange developed the view that the silent cockpit was a better system as it allowed maximum situational awareness outside the cockpit and they felt they had more mental 'reserve'.
We never really got to try it because my own company made a determined shift towards manufacturer procedures (including Airbus), which required maximum talking.
I would like to see a reduction in our flight deck chatter because I find it distracting and it does not necessarily fulfill the intention. The views expressed have certainly given me some perspective.