Does the "viper rig" include the beams or do you mean essentially the Taipan rig?
Actually Buccaneer, the F16 rigs are not the same as the Taipan rigs.
We started out with the Taipan rigs (with an added spinnaker) but soon fitted longer spreader arms (not allowed by Taipan class rules), raised the hound fitting (not allowed by Taipan rules), fitted a larger squaretop mainsail (not allowed by Taipan class rules), hoist the mainsail to higher points above the mainbeam (not allowed by Taipan class rules), have a different width distribution along the mainsail (not allowed per Taipan class rules), etc.
Over the years the F16 rig and Taipan have diverged although some convergence was seen when the Taipan class voted to accept their new squaretop mainsails (F16 spin-off). Both classes still use the same basic bare mast section but increasingly differ in the way they are fitted out and how they flex in combination with their difference mainsails.
They are becoming increasingly different engines.
Of course each vote in the Taipan class to open up their class rules to allow for these F16 inspired changes will see a momentary converge. That is true.
The Taipan rig was a great starting point, absolutely no doubt about that, but there has been significant (and specific) F16 related development.
Wouter