...I've seen MJ twice. The first time I saw Frost; the second time, I saw his standby, Aramie Payton.
Frost is very impressive. I understand why he won the Tony. However, I actually preferred Payton. Frost's "impersonation" of Jackson is slightly truer to life, but Payton is the more assured vocalist with clearly superior technique and a better actor with the ability to craft an arc more dynamically--admittedly, some of which is because he doesn't imitate Jackson quite as closely.