I think the Trackback model is "better" in that it doesn't require a central service to poll everyone, but the implementation of Trackback (no security -- you can post Trackbacks as anybody else!) is poor enough that something ought to replace it.
It's the standard centralized vs. decentralized argument: we get security on LiveJournal because everyone is authenticated, but we pay for it by depending solely on LiveJournal. Technologists (myself included) hate centralization but users don't seem to mind -- see, e.g., closed IM networks, "pinging" weblogs.com, anti-centralization bloggers happily using del.icio.us and Flickr tags, Apple hardware.