I've got cork insoles from Super Feet going on ten years, they're fine.
The boots you've got sound like they were too big to begin with, given the vast amount of room you have now that they are packed out. My last pair had 469 days on them, clearly VERY packed out, but that little bit of slop was handled for a few more years with the addition of a thin insole from the drug store.
Also, for all that everyone carries on about stiffness, I went from a flex index of 60 to 110 and didn't notice a huge difference, though granted there was a summer in between. Possibly if I skied them the same day I'd feel it.
My new boots now have 73 days on them, still really really snug. In fact, really weren't entirely comfortable until day 50. But then, I didn't have them cooked because I wanted the molding to happen from skiing, not standing. I don't know about anyone else, but when they tell me to get in a skier's stance in the shop it never feels right.
My boots are mondo 25.0, but my feet are 9.5 to 10, which comes to a whole lot smaller boot size than the size on conversion charts. They have an adjustable last that you adjust with a screw on the bottom of the boot.