I test drove an R-Spec before buying my 4.6. The R-Spec does have a firmer ride, but it still feels damn big. I think it depends on how smooth the roads are where you live - the R-Spec is pretty uncomfortable on rough surfaces.
It sounds like you want a sports sedan, and the Genesis, even in R-Spec, is not that - it's a big GT car that is perfect for cruising down the highway and making long trips comfortable.
For context, I daily drove a 2000 Mazda Miata before buying the Genesis, so I am used to a firm ride and tight handling.