Hi.... your maths is terrible... 1.2m square gives approximately 15.5 square foot.... The recommendations for HPS are 40w + per square foot... generally...
For the GN006 disco lights having spoken to Daniel at GrowNorthern he recommended 3 to 4 units for a 2.4 x 1.2 metre tent.... So you are bang on the money as the riff-raff say....
I did warn you about the maths, thanks for the info..