It should be very interesting to see because I remember over at overgrow there was a disscussion about the cage garden from omega, and many thought that it was not good for cannabis but was excellent for a smaller crop like lettice.
It will be interesting to see what type of results your buddy gets.
http://www.omegagarden.com/Basic_Omega_Garden_Model_10002.html
I just found out that these gardens are only 5.5 feet tall in total, with a light inside and plants on all sides, how can you possible control the stretch, you could not have plants any bigger then 2 feet when they are finished.
Also to get 240 oz, you would need to have atleast 5-1000 watt hps lights. 240 oz's works out to like 15 pounds, but it says that each unit only holds 2-600's. It is not the amount of space that dictates your yield, it is your LIGHTING
My advice would be to tell your friend to reconsider because i really do not think that these are good for growing MJ or even tomatoes and I think that he will be very dissopointed growing MJ in this, but if he insists, please tell him to be careful.
Either way good luck and I hope everything works out.