[Wavester]

They both have there good and bad points, one problem I have seen with drop stitch floors is if you get water in them (or when) they can be more difficult to dry out and can be prone to mildew. Bottom line is I wouldn't buy a boat just because it had a drop stitch or I beam floor. It's just one factor in many.
Fyi Sotar I beam floors seem much more stiff to stand on then hypalon floors, could be because of the material.