First of all, of course the ballot is preferred to the bullet.
The ballot however requires a certain type of person to put him- or herself up for candidacy. Such a person is necessarily of a particular psychological profile. That profile is only a small sub-section of the populace. Balloting -- in and of itself -- prevents realization of government 'by' the people.
Furthermore there are the obvious drawbacks: financial wherewithal, rhetorical adroitness, media visage.
Finally, the campaign is a contest. Many are attracted to the blood sport of it. That contest unfortunately drives the candidates to desperate measures -- not only the attack ads that poison civil discourse, but also the unavoidable compulsion to make promises and to take positions whose purpose is merely to win the election.
These reasons lead us to believe that sortitional selection of policy-making bodies will be the equitable, inclusive and wise 'next step for democracy'.
Like every other measure, visionary leadership would be as prevalent in a proportionally representative legislature as it is in the general population. Some may criticize this fact by saying that this is exactly why we force candidates to engage in combative campaigns … so that voters can choose the ‘best’. Unfortunately what is chosen in that case is ‘the most combative’.
But more important than 'visionary leadership' among the legislators themselves is the fact that visionary leadership will be available, as it is now, from outside sources -- from lobbyists, citizens, leaders of all stripes and other petitioners. The actual architects of most laws in current legislatures are rarely the elected congresspersons but instead their staff and their various committees of advisors. The Senators and Reps are simply the deciders who make the choices among all the options presented. Quite rarely is leadership coupled with electability, which is the precise point of sortition -- to remove the influence of money, influence-peddling and power-brokering from the process by which our leaders are selected.