Due to his lack of international (test) experience, I'd have a hard time calling a player who has a great record (and don't get me wrong, his record is awesome) in the county/state/province game "great" or him being a "star" player.
His international limited overs stats are a bit misleading since the majority of his games have been against fellow minnow countries (Bermuda, Canada, Ireland, Scotland, Kenya) but the half-century against South Africa in 2007, the 30-odd against Sri Lanka in 2006 in ODI's and the collected 22* against us the other day in T20 shows he at least has talent to play at that level.
As with all players, consistency would be the possible problem. Many players can do 1 pgreat performance and then string 4 or 5 mediocre or poor performances together.
RTD wont play in tests for SA, they have far too many better players, which is a shame cos I think he could be test class. Not top class, but a pretty decent No.6 and 4th seamer added to his very good fielding skills.