I went from a 250 Virago to the 1100 Virago. No surprises. What's nice is that your 535 and the 1100 are so similar in layout. It will feel comfortable almost immediately. You'll notice the additional power right away, but it's not overwhelming. The 1100 is slightly more top heavy so easy does it on the slow turns until you get accustomed to the balance point. Also don't park it in neutral on a slope, it will roll off the side stand.
I checked everywhere when I was shopping for my upgrade. The price difference between the 750 and 1100 was only a few hundred dollars, and insurance rates were pretty close as well. Physically, almost everything is identical between the 750 and 1100 aside from the cylinders and a few minor electrical differences as well the 750 doesn't have the auxiliary fuel tank or the fuel pump.
The major advantage that the 1100 has over the 750 is torque, and that shows up most when riding 2-up.
I average about 4.9 to 5.3 L/100km with an all time best of 4.5 L/100km. That's calculated over 10,000 kms ridden since Feb 2012