I know the 400 HPS puts out higher lumens, but I figured since the T5 is closer to the plant wont the efficiency be better.

What I mean is that since the 400 is x feet away it only uses x% of its lumens while since the T5 is y feet away it uses a higher percentage of its lumens...

I'm not saying I think its as good as a 400HPS but I feel it would be somewhere equivelant to the 300HPS range being so close to the plants