Isn't the whole point of shooting a 'Hawken' style rifle the fact that many of them ARE designed to be 'historically' more correct and shoot the patched round ball instead of sabots or conicals?

Depends on the rate of twist in the barrel...most modern replicas of Hawkens have a 1:48" twist; they were designed to shoot both round ball AND conicals......some shoot conicals and balls well, others shoot only balls well, and some shoot both well. The 1:48" twist is kind of a "compromise", with all the options out there.
To shoot PRB, most rifles prefer a slower twist (like around 1:66 or so).
Depends on the game, also.....if I were hunting bigger game, such as elk, bear, ect, I think I would like the extra energy that a conical would give me, esp. if I were shooting a smaller caliber rifle.

That's true! I know some of the Hawken's are 1:48 and can shoot either pretty well - tho I know for 'the most part' patched RB's like a very slow twist - as you said - like a 1:66 or 1:60 like my Lyman GP rifle has.

Not necessary, original Hawkens were also 1-48 twist and they shot patched balls out of them...The big difference is they were also cut rifling, instead of button rifled, so the rifling was .012-.015 deep instead of .006-.008 deep...This holds the patch better...

They also probably shot less powder than many do now and for decades they only had FF powder, not FFF...

A factory rifle with 1-48 rifling can shoot a round ball with good hunting accuracy and once you get to a .54 it will easily take elk and bear....