Are they 'bad' in the sense that they won't grow decent bud? No, it's just that led's have evolved significantly over the time when 'blurple' monochromatic diode fixtures were all that was available.
The reason to look closely at the specs is that current tech diodes like a Samsung lm301h produce about twice the photon output your plants use to grow for each watt of electricity it uses compared to 'blurple' fixtures.
So, getting back to your question.
480 watts of top-tier diodes will rock a 4x4. Domestic companies offer excellent product choices and warranties, but if you're willing to accept some risk you can find reputable products from China for about 1/2.
800 watts of HID(HPS,CMH) would also work well.
If you're stuck using 'blurples', I'd suggest at least 900 actual watts consumed for that space.