I haven't read the article but some clarification. The practice of combining Viognier and Syrah started in the Northern Rhone, Cote Rotie in particular. Notice I said 'combining'. In Cote Rotie Viognier was traditionally co-planted with Syrah and picked at the same time. The grapes where then ferminted together.
The legal limit in Cote Rotie is 20% Viognier. For many years this was simply called a 'dodge' by the wine press. A way for the local growers to get away with adding the cheaper Viognier and not having to replant. Much of this type of stuff goes on in Italy where all kinds of inferior grapes are allowed to be mixed in the fields in a political gift to growers.
In the 1980's Guigal came out with the La, La's and La Turque in particular had Viognier. The conventional wisdom began to change and winemakers explored what Viognier was brining to the blend. The term "co-factors" began to be used and Viognier was credited with locking in deeper color in Syrah and in giving a lift to floral flavors. Bringing out violet in particular from the Syrah as well as adding some peach and apricot notes from the Viognier.
Many insist the benefits of Viognier are only possible with co-fermintation. They say that simply adding the Viognier does not produce the floral lift and deeper color, only adds the apricot and peach of Viognier. Torb, Pauly or Aussie probably know more than I but I believe most Aussie Shiraz is blended not co-ferminted.
Personally I really like the wines that are co-ferminted. I had a 2002 Lagier Meredith last night for instance, that had deep color and a nice violet note to go with meaty blackberry, iron, spicy pepper and provencial herbs. IT's more subtle to me than those that have been blended.