Chris (
@Kiwizinho) has already mentioned quite a number of new features and improvements since v2. Some more that would spring to mind include
- the Colour Wheel for better control with colour corrections
- Control Lines, which have brought welcome Control Point functionality to gradients
- DxO Wide Gamut, a significantly larger colour space than was previously used as a basis for colour rendition
- a more informative and sensitive histogram
- more options for tailoring your workspace according to your needs and tastes; faster access to the corrections you regularly use
- at least limited support of Fujifilm Trans-X sensors (largely irrelevant to me personally, as I don't run parallel systems, but welcomed by many who do)
Given the upgrade discount you received and the extent of new features and improvements, I'd say v6 would add considerable bang to your post production capabilities. Just make sure that your computer hardware meets the system requirements.