Verdict after 5 races:
Ricciardo has been strong in qualifying, he’s beaten Vergne 4-1, including a 6th place to an 18th for Vergne. This shows he has the raw pace to beat Vergne, however, he has had some bad starts (must be an Australian thing), and a bit of bad luck with front wing damage on the first lap both occasions he qualified in the top 10. His comeback in Australia and some of his racing in Malaysia was good but other than that his race pace has been quite poor.
Vergne showed that he is very good in the rain in Malaysia with an impressive drive to score points. He has beaten Ricciardo by one position in the last 3 races when they have been in similar positions. So vergne arguably has the better race pace at the moment.
The Toro Rosso looks the worst of the midfielders so it will be difficult for either of them to score amazing results. I doubt they are trialing for the 2013 RBR seat but rather 2014.