There is a simple and obvious implied benefit to be gained from moving from our existing "opt=in" system to one of a presumed greater benefit, and that is a greater provision of organs for transplantation; we have a desparate shortage of donor organs in this country.
In the UK, the waiting list for transplants is increasing year on year by around 8%, and at the same time, approximately 1,000 people a year are dying whilst on the list for want of a viable organ for transplantation.
We do have a much lower rate of donor organ donation in this country compared to others, such as Spain. Essentially, we have 3 options ; 1 do nothing, 2. Big advertising campaign, central computerized donor registration, or 3. Change to a Presumed Consent system.
There are some family cultural and societal reasons why a presumed consent system might be resisted. Personally, I would favour trying a more aggressive advertising campaign, coupled with changes in donor registration first before moving to a presumed consent system.
Couple of links on the subject:
http://www.guardian.c...tion-presumed-consent
http://www.bmj.com/cg...ong/338/jan14_2/a3162