I've just started homebrewing. The guy at the local homebrew store swears that I don't need any secondary fermentors, that I should just leave my brews in the primary to age and then bottle condition them. I have a plastic bucket fermentor and two 5 gallon PET bottles.
I plan to brew some high gravity beers (RIS and an English Barleywine) as well as a dry mead. Since I'm going to be aging a bunch of batches simultaneously I'd rather not spend ~$40/each on glass carboys.
I want to leave them in the primary for 4-6 months, then bottle condition them after that. Is this a bad idea? What's the worst that could happen?