I still use a Newtek product called Speed Edit for my current HD video editing on a PC but it is not a live switcher so that part for me is lost.
For most people, live editing was only really beneficial when it was impractical to do offline editing.
I used to be a cameraman on a 4 camera setup and that was usually edited live, but all the cameras also ran tapes in case a mistake ruined the edit.
You do run the risk of perfectionism creeping in with offline editing.
If you are broadcasting live then obviously you need live switching. The Roland V-4EX looks quite nice, though it can't process 1080p.