Preface: I've used Pro/E full time for 4.5 years. In order, I've used 2000i; WF3, 4, & 5; creo elements; and Creo 1.0 (back to creo elements).
My quick opinion is that moving from WF5 (or later WF) to creo elements/pro 5.0 is a waste of time, but moving from WF to Creo 1.0 is a smart move. I have no empirical data, yet I'm confident in saying that the improvements were saving me time (I was designing plastic injected clips, buckle, fasteners, etc.). I say "were" because at my new position Creo 1.0 is not an option, and I miss it. I'm excited to see Creo 2.0 in March. I'm not going to be able to use it much, but I will play around with it.