I would run beds but I'm running perpetual, looking at running beds soon. If your not having to move plants around its all good....
Even if I have an ebb tray I'd rather run containers in a bed and not move them but recently I haven't been able to , more room for roots to call home is a good thing.
Depends on how big u wanna go, a month veg only a 10 gal is enough, but trees w tons of veg and Multi lights the brute would be what your after.
70 gallons of Rez for a four plant flood table is way overkill... You could get away with running 1/3 of the solution and use 4 10 gallon rubbermaids filled with yer ewc-ton-chow mix. i would recommend keeping the 4x4 for sog and run an rdwc for four plants under a 1k. W 1 month veg max. Yeild will easily hit 1.5p with that rig and is respectable with little expierence.
I would run more plants w less veg time in a 4x4 than waste all the nutes on only 4 plants, when you could get away with using a smaller tub in the big 4x4 and run less nutes in your big Rez till they built up n get lanky n ready for bigger containers, then seperate out of small tote , set into 4x4 and then continue veg filling up the Rez to where it floods 2/3 's ... Then when they get to flowering.. Fill the Rez up till the table can't hold any more.
That's what I do to save money on nutes...