For years people believed that frozen foods had significantly diminished nutritional value. We now know that the decrease is negligible. (
http://www.fsis.usda.gov/Fact_Sheets...ing/index.asp). Freezer burn is an esthetic issue, not a sdafety or nutrition issue. Frozen foods are very nearly as nutritious as fresh in general. Freezing can kill parasites that might otherwise affect your snakes. Freezing also makes it impossible for your prey items to fight back. In spite of what you might think, snakes dont "enjoy" hunting or killing food. They do it instinctively. Very few creatures in nature hunt or kill for fun. I believe it's just humans and chimps, although there may be a few more.
As far as I'm concerned, there are no pros to feeding live other than getting to watch a more natural behavior. That is not a "pro" for your snake...only for you. F/T feeding is better. Feed live as a last resort.