I purchased a 12x16 ft shed a few years ago, and it had trusses like the ones in the first pic. I immediately notice that the center of the roof was already starting to bow down. Checking the trusses, I could tell they were installed very cheaply. I decided to beef up the trusses myself, with 6 2x4's, on the longest part of the trusses, and added support half way on each of them. I live near the White Mountains in Maine and we have snows that are in multiple feet each year. I don't think I had much more than $50 dollars to make everything right. Spend a little bit more and ensure you will have no problems.