There really isn't nothing wrong with Miracle Gro.. its usually sphagnum peat moss and forest composted products just like most potting mixes. I don't think it's too hot for the plants, they actually look pretty damn good. I wouldn't panic about them, just take preventative measures. If the lower leaves are yellowing and its slowly progressing up the plant it's usually NITROGEN. I wouldn't take the plants and wash the roots just to put them in Fox Farms, would probably cause more stress and FF is almost always hotter than MG. If I were you I would've tried to get a male and female of each strain to cross, but you could always cross the Acapulco and Colombian. If the seeds are what he says they are it's very unlikely that you will see those genetics again, not ones that are 30+ yrs old. I would do everything to preserve them.