I've read several of the posts on this subject from this group and it seems some people are discouraged from installing a whole-house water filtration (softening) system because of the belief that soft water will adversely effect or increase the corrosion on their copper plumbing.
The interest my wife and I have in installing a whole-house system is primarily health related, specifically eliminating chlorine and other toxic contaminates from our water. I have to admit I was discouraged with the whole-house system after reading the posts about the corrosion problems.
For the interest of all that are thinking about a whole-house system but are discouraged because of the belief that soft water is more corrosive than hard water, I have good news. I found a group, the Water Quality Association (WQA) that did a study along with the Environmental Protection Agency (EPA) on this very subject. Their findings were that soft water is not more corrosive than hard water. In fact, they found soft water to be better suited for plumbing and their fixtures because of the reduced scale formed on pipes and appliances.
You can read the article about this study here http://www.wqa.org/sitelogic.cfm?id=366
Hope this helps someone,