Many here use MG and smoke it. I started off using it and it was a real pain in the arse due to the time release nute's MG has. Once I switched over to FoxFarms and monitored my PH closely, the plants stabilized and are growing nicely.
Couple bad things about MG is you can't flush the plants in the last week of all nutes before harvest and as well, if you have to "flush" the pots they are in due to nute lock up or sodium build up, who knows what stability you will introduce with those time released nutes.
As to tin foil, I was told to ditch it aswell. I went with Mylar, and honestly, I visibly noticed a difference. You are better off with a white wall or mylar over tin foil. As another poster told me, the tin foil will wrinkle easy and could cause reflective surfaces that become "hot spots" on your plants..
Take it for what this is worth and good luck!