Closed versus Open Adoption

So.. Closed adoption basically cuts off any communication or identification between birth parents and adoption parents and open adoption means to have an open relationship between the two.
I guess there are pros and cons for both, but I really don't know, since I am very unexperienced in adoption.

CLOSED: pros for birth parents: provides closure.. and privacy & cons: no choice in the adopting parents
pros for adopting parents: no chance of interference later in life & cons: no history on child.. might face a lot of explaining when your child gets older.

OPEN: pros for birth parents: less guilt, comfort in knowing where child is, an increased ability to have a role in child's life
& cons: no closure
pros for adopting parents: probably an easier life for the child, understand the child better through birth parents, & cons: a bigger chance of interference.. Will the birth mother want her child back?

I know a family who adopted openly and is now facing their child's birthgrandmother, who is fighting for legal rights to her grandaughter. They want to completely take away the baby, without any interference from the adopting couple. Once you've fallen in love with a child, you can't just give it back and once you've given up your rights to another loving couple, you can't take it away. I feel like closed adoptions could potentially remedy this problem. However, a lot of women probably would have a harder time giving up their baby completley. Without both options, many people would be drawn away from adoption. So, it's not a matter of which is better, it's a matter of which works best for each particular situation.