The ds100 would grow 1-2 plants in that space. At 4 sq ft your space would only be getting 25 watts / sqft ... The ds200 would allow you to do a better job w/ 2 plants in that space ... you could do more if they fit ... the ds200 would put out a little more heat if temperatures are an issue ... w/ a little practice w/ a ds100 and that space you could easily produce 3 ozs every 3 months ... the ds200 would probably increase the harvest by an oz or two so if you can afford the bigger light I think you would be happier. I started w/ a ds100 in a 2x2 space w/ 5-6 plants that gave me about 3 ozs. Learned that 1 or 2 bushy plants could out produce twice as many scrawny ones ... Advanced are good people to deal w/ and to me, having a great warranty is worth the difference in cost between them and a knock off ... good luck and I hope you start a journal for your grow.
"MrPiggy Hug"