I think here is the answer to your question. The dropped A frame will likely be stronger. Here is why.
The stronger Frame rails for a trailer will be an "I" beam either made by two "C" channels welded together or the Rolled at the mill type (the stronger in lbs per sq in terms)
These types of frames will almost always have the dropped A frame in my experience.
A Frames are usually Rectangular Tubular Steel. For this to be mated to an "I" beam creates some welding difficulties at best. Therefore they are "dropped" and welded underneath.
If the frame on your trailer is of the rect. tubular steel type, it is strong for sure but probably not as strong as the one piece "I" beam. And the A frame would be welded to the ends, as in the non dropped type, with Butt welds, which on the thickness of material usually used for Tubular steel in RV's are NOT as strong as the deep penetration Fillet welds you can get on the much thicker steel of the dropped A frame type.
There will of course be many variations on this theme And both are strong.
In my opinion the Dropped has several advantages and is ultimately some percentage stronger. But without measurements and drawings it's impossible to tell for sure. In any case the differences may be great or small depending on the welds and the material.
There is more than enough strength there to carry anything you need. The photo that is on this thread is without explanation, we dont know the circumstances or how the unit was built, if there was a serious mfg flaw or what happened. It;s a nice photo but irrelevant to this discussion...and this occurrence is VERY VERY rare.
I think you have much more to worry about with your RV than this. This is a time tested design that works very well. And it is not new. My 2004 Innsbruck is of the drop frame design. So the argument that this is a new and "cheap" out for the MFg's doesn't hold water.
