I've been in IT for many years and have been involved at the project management end of some largish rollouts.
I agree Baswell that issues routinely occur with these types of rollouts but I believe they could have done more to ensure a smoother cutover.
You always need to conduct load testing prior to cutover, how did they go about accomplishing this ? Clearly what they did was not sufficient.
The test site should have been up for much longer at least 1 -2 months. Cutover date should have been delayed to allow for this.
My approach would have been to have a parallel implementation of both systems with a cut off date for NFW.
This would have meant a gradual transition, realistic load testing rather than simulated and instant rollback in case of serious issue.
No doubt tricky to achieve but worth the effort IMO.
On positive note I do think they have made the right choice going web based as its going to allow for rapid and simple deployment of additional functionality. (should benefit all of us hopefully)
Lets face it updating a Windows app on large scale is a pain in the neck. No doubt why NFW hasn't changed in a long time.