as stated above, I'm growing organic i have a 4x4 with a 630w cmh organic no till in 4.5 gal square pots pulling 5 ounces per plant (usually a little more but rounding down... on a 5 week veg after clones root.
could do a 2m x 2m tent with a 4 plant screen of green or heavy LST, 4x 600w hps, unless you got the cash to splash on LED
A 10 foot by 10 foot room with 5 1000 watt single ended hung vertically in an X pattern with 4 plants arranged like so:
XOX
OXO
XOX
Lights are Xs, plants are Os.