I guess it depends on what you use the 5K for. This update has lots changes to the DSP options, so if you use any of the DSP tools, this is a major update. And, honestly, without the DSP tools, I'm not sure why else you'd use the 5K. But, as ever, YMMV.
Existing 20band EQ and changing profiles works fine still with current 2.x firmware. I have no desire to change or adapt to their new annoying and unwanted(to me) changes.
If it works, don't fix it.
Though, it seems they did make changes to allow for single use of 20band, and made the new 10+10 EQ thing a mode, and not the only EQ options. Maybe that is why they delayed it much longer. Though, perhaps it is a transitionary step. In the future, fully removing the single 20band mode perhaps, seems they are keen to do that, to make it work identical to the T71 higher model DAC. That was their intentions from the start.
I do have a spare 5K i am not using atm, (replaced it with a different DAC that supports Optical in) once they work the initial bugs out of the 3.x firmware, may update that unit just to play around with things though.
I am surprised, though, happy, they seemed to have taken to heart feedback left by me, and others who spotted their 5K Update Plan thread.
They do make a very good product, but they have competition. Fosi Audio has reached out to me and many others, and started a dialog via group chat for user feedback on product development and improvement. They are making some compelling rivals to Qudelix, Fiio, etc.