So many moons ago I messed around with the whole Mr Beer thing and still have a pair of their kegs. After a homebrewing hiatus, I bought myself a 5gal kit and started doing extract batches. Partly out of laziness and partly due to the data I saw, I went with the extended primary method and thus haven't bothered with a secondary yet. Previously, for most of my batches, I have had them in primary for 3-5 weeks and then gone straight to bottling. But what if I want to condition with other fun stuff such as dry hopping, fruit, oak chips, etc.
I realize it wouldn't be the right choice for extended aging due to air permeability and the like, but for relatively quick stints (1-3 weeks) would it be reasonable to use the 2 MRB kegs as a secondary when I want to add the flavorings and such?
Mind you, I'm not exactly churning out world class beer so there's a big difference to me between "that's a really bad idea" and "you'd be better off using a traditional glass carboy with purged head space, but most people won't taste a difference"
Another possibility that someone mentioned was adding this sort of stuff to the primary after a few weeks, particularly with dryhopping. I'd imagine that in terms of worrying about the CO2 scrubbing the flavors that this would be no different than doing it in secondary. On one hand you have the issue of sitting on the lees, but OTOH one of the beliefs of the extended primary is that several weeks won't hurt anything. One concern would be splashing when putting this stuff into the primary vessel, but you're going to have some air exchange when racking anyways.