I started with V6 so I don't know what kind of transition you will experience going from V5 directly to V8. I also previously upgraded from V6 to V7 before moving on to V8.
Out of all of the versions, I like V8 the best. Not sure whether it's because I understood V6 and V7 and gave them a pretty good workout before moving on to V8, but it seems to me that V8 is not only more user-friendly but also has several enhanced features that make digitizing even easier than before. No sense me pointing out those to you because Bernina has done an excellent job of that in its release notes that you can download from their website
www.bernina.com/Bernina/media/Support_Filebase/Software/Embroidery%20V8%20Trial%20Download/English/ReleaseNotes.pdf and read through.
Also, you can go to YouTube and type in "Bernina Software 8" and you will find that Bernina is doing YouTube tutorials on the various aspect of Software 8 so you can watch them to get a sense of how it works and if you think it is something you'd like to be using.
Finally, Bernina is making available a 30-day trial version of the software. After reading through the Release Notes and watching as many videos as they had posted at the time, I downloaded the 30-day trial version and gave it a good workout (I used the release notes as my guide and then just played with each feature) before I made the decision to upgrade. I did set aside a bit of time EVERY DAY to play with the software to see whether I really liked it or not.
I think Bernina Software 8 has many more features than V6 ever had and has made digitizing a lot easier for me, so if you like the format (what you see on the screen), you may very well consider the upgrade. I like to make my own designs from scratch but I can imagine Software 8 also to be quite useful if you purchase designs and want to adapt them to your needs. Knowing what I know about both V6 (in my case) and Software 8, there's no doubt in my mind that I would make the leap, at least from the perspective of ease of use. But try it yourself before you commit. Like anything, though, it takes practice to become proficient! But then the sky is the limit--you could even design an applique block completely in Software 8 and watch it stitch out on your embroidery module!
Hope this helps.