Avid has always had 4:4:4 I use it everyday.
It is an uncompressed RGB format, this DNXHD444 I dont understand, it must be a compressed version for dual link RGB.
I tend to use DNX-185X for 90% of my work, but If i need to go back to film currently i work in RGB mode and output to HDCAM SR.
If there is DNXHD444 as a compressed format similar to DNX-185X then that would be a great achievement as the uncompressed mode sucks way too much bandwidth and storage.
I would however like to have the ability for LUTS and DI on media composer/symphony and I have had DS for 6 years now and no one in my office uses it, as it is a totally different beast and doesn't easily integrate with my unity.