Members of our Planning sub committee often discuss via phone and email, planning applications coming up at the next meeting. This often includes input from one of our officers, and is usefull in highlighting local issues that the unitary authority may not be aware of. I have often used this approach to draft a response. It also allows members to consider the applications adhearance/or not to core planning policy in detail rather than rushed in a committee meeting.
However I always present the draft response at the committee and have often allowed ammendments to that response by the committee, who then vote to make a final council decision.
It needs to be remembered that what if members of the public wanted to speak at committee? This could bring something to light, not previously known, and by submitting it before the committee it could be considered as pre-determination?
Individual members should also remember that nothing prevents them from submitting their own comments seperate of the council, even under their council identity!