hi maw,
i can't give you long term results as i am only 15 months post-op for a l4/5 fusion. I am just now beginning to be able to function at about 80%. Its a long, slow process.
It is true about the levels above and below taking over for the fused part. I have learned to do things without engaging my back, but its tough.
i squat rather then bend. Or kneel. And,if i do bend, i bend from the hips. I don't know if this will save the rest of the back from damage. But i try.

good luck.
sims