I edit in whatever format I shot my Scarlet in with the exception of 1K@120fps (waiting on EPIC upgrade).
You can keep your files at 3K in FCPX.
You could also just proxie them as well which brings them down to smaller than HD anyway.
I agree with most of the machine issues here.
But I get that Premiere Pro and at times Avid MC/Symphony too and thats with a Nitris DX 😛
My fave FCPX station is a 2012 Mac Pro with 32GB RAM, 4 x SSD, SAS > GRAID eS Pro and an Nvidia Quadro 4000 x 2 plus a RED ROCKET card.
Average length of projects 20 plus minutes.
Mind you I round trip to AE and Resolve a lot so its not entirely an FCPX station.
Will things change with the tube?
Cant wait to find out 🙂