Lumen wise
4X1000= 1@150,000; 600,000
6X600= 1@90,000; 540,000
Not a huge difference.... I think it is all on preference.... Them 600s would be pricey.... I like 1000ws. Nothing compares to 1000ws for density and size.... If I had the cash though, Id put 2 600ws for every 1000w.....