Hi Quercus,
Stearns & Foster and the other major brands tend to use some fairly low density polyfoam in the comfort layers which will soften faster than higher quality materials. It’s not uncommon at all that in the 3 - 5 year mark they need to be replaced because foam softening leads to the loss of comfort and support (which isn’t covered by a warranty). This is especially true with their mattresses that have thicker comfort layers so perhaps your accident wasn’t such a bad thing.
This is the support layer which is not normally the weak link of a mattress (a mattress softens and breaks down from the top down) and it’s also a high quality material so it would last for many years.
Wool sensitivities generally involve contact so you may be fine with wool quilting. Some of them may be able to provide you with a sample of their cover that you could wear against your skin for a day to make sure you would be OK with it.
The better options in the Oakland area I’m aware of are listed in post #2 here. There are some good options in the general area but I would check websites and/or make some phone calls first to make sure they have some mattresses on their floor that fit your general criteria.
Bare latex will generally sleep warmer with an unquilted cover (although it’s still more breathable and cooler than other foams) but it will also depend on all the other combined factors that can affect sleeping temperature including the softness and thickness of the comfort layers, the type of mattress cover, your mattress protector or any mattress pads you use, and the type of sheets and bedding you use (see post #2 here).
Good luck … and I’m looking forward to finding out what you end up choosing. Of course if you have questions along the way don’t hesitate to post them.
Phoenix