I tried the remix decks with an F1 and a midi-fighter and while they were fun to play with I did not see the reward vs effort to integrate them into my live sets.
If I do a “normal” mixing set the sample player of Serato is highly efficient and way more hassle free for me.
If I do a remix set I rather use Ableton Live or even NIs own Maschine (or both) and mix then via an external mixer.
The in-between workflow of the remix decks is not my cup of tea, as it is not quite the freedom of Ableton or Maschine, but also not as simple as a sample player.
Also I can simply mix 4 decks and still use all sample player slots in Serato…
But that is my workflow and style, I guess for other people the remix decks would work fine. I just do not need them in my setups.