Wasn't the Viggen an inherently stable aircraft despite its' early canard-style (albeit not all-moving) layout?
One of the criticisms levelled at earlier 'pure' delta aircraft (such as the Mirage III/5) was that they bled too much airspeed in tight turns. Not sure how well (if at all) this was overcome with the later Mirage 2000...
On the other hand, GD/LM claimed that the double-delta 'cranked arrow' layout of the research only F-16XL (or F-16E) made canards unnecessary. Always wondered about this claim!
I think the 'secret' to instability (and thus turning performance) is loading the c.g. as far aft as possible. The 'normal' F-16 is a good example of this in a conventional layout. Canards just provide an efficient way of controlling the pitch-up tendency.