Having recently had the opportunity to try Voyager under MOS, it is my opinion that it has not aged well. The MUI4 incompatibilities are severe, almost crippling of the GUI. IBrowse's JavaScript implementation appears to be mostly current as of last year, and its Flash plugin is pretty much on par with Voyager's, as far as level of Flash version implementation goes. Voyager does have the APDF plugin, which is nice, but it's obsolete compared to the latest standalone version from the MOS FTP.
It'd probably require the same amount of work as AWeb or IBrowse to get it up to standards compliance, but given that its development seems completely dormant (rather than just painfully slow), it doesn't seem likely to happen.