There are a lot of differences between the Exo and the Exo Pro not just the bars
The pro's are mainly aluminium and the Exo's are mainly steel this impacts on the weight as the Pro's are a lot lighter
The clamp for the knee bars are different and the pro's come with cuffs so the price difference is very small if you allow for all that
If I was starting out now I would buy the Pro's unless money is really tight
Having said that I have just bought a set of Exo's and I must say the build quality of the steel ones is superb and they are good value for money just the Pro's are lighter which is always better
Jason