Personally I think this is more a case study in how not to do PR. We have a company (well city) announce they are moving to a competitors product. Do you
1)Give them a call and try and see if the relationship can be salvaged?
2)Failing that allow them to go ahead with the migration, but let them know should they decide compelling featutre you offer is important, you'd be more than willing to help them migrate back to your offering in the future
OR
Write a press release, suggesting that your customer is making a bad decision?
To me, it seems that criticizing a past customer based on there choice to use another service provider is simple bone-headed. I mean you can say these things internally, but to publish a press release?