I think the problem enlies with the suspension (after checking tires, balancing etc, head steering bearings etc) the variable weight springs are very soft initially then go into a harsher part of the spring travel. i never had any stability issues with the stock suspension, i just didn't like the floaty feel when transitioning the bike from fast left to right, I'm 86kg and had set the rear sag on the 3rd ramp from the hightest point down. The front end of the 790 has very large rider sag numbers (54mm from memory) so too much rear preload will take too much rear free sag out, so id sugest dropping a few clicks lower in the rear preload. you weigh about 88kgs, so thats 10 more than me, i was happy on the 3rd or 4th click down. The thing with putting to much preload is, you reduce the free play/static sag, and your getting a mismatch from front verse back. There is a little trick that could be done with the stock suspension and that would be try different weight oil in the forks, stock is 5W, could try 7.5 etc if you had the time and ability to try this. This was going to be my first port of call but after feeling the amazing difference with the Nitron shock, i went down the Matris route but have quite got the front end perfect yet.