There are quite a few "rumours" about the differences between the Viper and the other F16's like the Falcon, Aqua raptor, Stealth and Aussie Blade. Most of them contain very little truth if any at all.

For righting the most important parameter is the weight of the mast and rig and possibly the amount of water sticking to the sails or that is inside the mast. A hooking leech can trap some water on the sail near the top and make a huge difference in righting weight. Differences in Hull weight etc are not really a factor at all.

An importance aspect to note is that all F16's use the same alu mast and as good as identical sails and rigging. This means that the Viper rig is basically identical in weight (and righting) to the others (excepting the Carbon F16 rigs). Then add maybe 3 kg additional righting weight to compensate for the heavier hulls etc (assuming a 130 kg Viper) and you're there. By comparison, 1 kg additional tipweight already results in 8.5 kg additional righting weight and this shows how much more important the rig weight is in comparison to platform weight.

At 75 kg you will be just a tad too light for righting in what most would call no-wind/no-wave conditions (0-5 knots, flat water). You should be fine in "normal" regular sailing conditions without using any right aids but with a proper righting technique. Carry a bag for safety and expect to not use it unless you somehow flip the boat in flat water and rather light winds.

Best advice I can give you is to arrange for a test ride on a F16 and simply try righting it alone; then you know for certain.

Wouter