Re: Two items that could save your life
The purpose of a hub adapter is to remove all runout in the sprocket. You should not need a spring if the sprocket is centered. I only use mine to prevent rubbing on my frame. If you have enough slop to need a spring, something else is wrong.
As far as dirtbikes using springs, that is not comparable because dirtbikes have suspension movement and sometimes need a spring. Bicycle frames do not have rear wheel movment to compensate for.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.