I've been shooting everything in 4K for about a year now. RED, BMPC, Canon, Sony... 128gb cards, 8TB hard drives, tons of lighting equipment
Oh yeah, forgot about the 4k monitor, and graphic cards you have to buy so you can edit your footage in realtime. 2 hours per card to upload footage, about 4-8 hours to back up your work onto other hard drives. Start investing in good hard drives... Lots of them.
Party's over for the run and gunners.