Your comment tells me that YOU HAVE NOT TRIED what I posted.
I tried similar setups on my longboards (longboard have the same physical behaviour as quadskates). And there are a thousands of longboarders who also tried what you wrote (hourglass, reverse cone, smoother bushing down…). What I worote is the result of my experiences, which confirm the theory and the oponion of all others longboarders.
You can read some stuff about bushings on silverfish.com
But if you enjoy your new setup, then just skate with ! 🙂