I did it fine without any issues. Was new to hikvision so can't comment on loss of features as I did it on day 1I haven't updated any of my HIK cameras or the NVR as all I read was horror stories, people seem to have major problems or features get removed, anyone else found this? Not upgrading firmware or software goes against the normal advise for most prducts.
With a quick Google you can see plenty of vulnerabilities so I wouldn't risk running potentially compromised firmware at all.