After just receiving Cp7, would it be worth it to replace it with Cp8?

I would love advice from seasoned forum participants on this situation...

We have a small workgroup that has begun generating its own training modules. To this end, we ordered Captivate several months ago for two of us in the group. At the time, Cp8 was not available at our company, so I received Cp7 and am now creating modules in it. The other person who was supposed to get Cp7 never actually received it because of a misunderstanding with our IT group. Now Cp7 is no longer available through our company, so she will have to get Cp8. We feel that since we are both newbies at Captivate, it would be better for us both to have the same version, so as to help each other learn. However, since we just paid for me to get Cp7, we are wondering:

• Are the differences between Cp7 and Cp8 really significant enough that we will run into problems if we try to help each other learn Captivate while using the two different versions?
• What are the main differences between Cp7 and Cp8?
• The bottom line: Is it worth the expense to get both of us CP8, considering we just recently paid for me to get CP7... and, if so, why?

If we find out it would be better to order Cp8 for both of us, we will have to provide a reasonable justification for the expense to our managers.