Having seen all three Burrs (Odom [9x], Harcourt [1x], and Smith [1x]) I think the show is in good hands no matter what. In many ways I preferred Harcourt to to the others (gasp!). Odom clearly has that star power and blew me away every time I saw the show. His voice is silky smooth and stands out.
Harcourt's voice is definitely rawer and took some time getting used to when you expect to hear something different but it's still incredible. What I loved about Harcourt's role is in each scene you could see the wheels turning in Burr's head and see the gradual transformation of his character. You understand every reason why Burr does what he does, and for those reasons I found myself rooting for him even more than I did with Odom. Odom's transformation, to me, seems more sudden and while it works, I prefer Harcourt's development better.
Smith, who I saw back in April, I felt needed more time to develop a unique character. His voice is great but stands out less and I felt his character blended in the most with the rest of the cast. When Smith was on, Hamilton was clearly the lead male role and Burr felt more supporting. After Room Where It Happens, Smith started to pick up the pace, but a little too late in my opinion. I didn't find myself rooting for (or even caring about) Burr that much. Again, not a bad thing - just a different way of experiencing the show.