VM 6 is night and day improvement over V4 (so was V5)
I did not like V4 and only bought it because it came with a promise of amazing things in the "soon to be released" V5.
V5 was very good and a massive improvement.
I am very happy to be on V6 and would not go back.
V4 you can't create any geometry, made it terrible IMO. I would need a containment region and would have to draw it in CAD and import again and start over. This could happen many times trying to program a single part.
OTOH if it is all for hobby and you can get by with what you have and you don't feel like spending a thousand bucks - why would you upgrade?
www.integratedmechanical.ca