The best advice I can give you is to read about it yourself and draw your own conclusions. Ed Frederick recently released a book called “Ten Seconds Inside a Tornado” and for the $20 it’s a good read to understand what it was like to be here in TV when the F3 (160mph) tornado struck The Villages in February of 2007. These are true stories from Villagers about the experience. Here’s a link to his site if you care to order it:
http://amworldeditions.com/AWE4author.html
But here’s my conclusion/opinion. All things being equal, yes a block or cement home is certainly stronger structurally.
But although there were no fatalities in TV from the tornado of 07, the many injuries (some quite serious) were caused by debris flying through windows, and some of it was like shrapnel from sheet metal shrouds around air conditioners that were torn apart.
So the weakest point during the storm was usually the many windows and lanai sliders that got shattered from the force of the wind and debris flying through it, and that was true for stick built as well as block/cement homes.
Best advice is to always have a weather alert radio tuned and a plan to go to a safe area inside your home when necessary.