I stayed on Primo E most of 2011.
I bridged with it at 2-400mg, and blasted with it at 6-800mg.
I ran it by itself as a bridge, and stacked it with either test, deca, or tren during blasts.
If you are wanting to make gains with it, I strongly suggest running some other stuff with it in decent doses.
I personally love it with some NPP and a good oral like D-bol.