I like the 4-6 week and then rack plan.
I think the long term troubles would arise more from the various breaks and hop bits than yeast. I've got bottle conditioned RIS that I'm just now starting to get to. It's been in the bottle since April on the yeast. I know that's a smaller contact area than in a carboy but like I said before I doubt the yeasts would contribute to off flavors.
It all comes down to what you're comfortable with since it's your time and resources that are on the line.
1°: Ginger Amber, Cider; 2°: Blackberry Melomel, Orange/Clover blossom mead, Banana wine; Conditioning:Cyser, JAOM, In like a Lion RIS ; Drinking: British Mild, In like a Lion RIS