The legs make you fast. You might enjoy going downhill on a bike designed for unloaded use and without load, but loaded in front just changes so much.
Of the three bikes you have provided links to, they all appear pretty similar in position, the bars are almost level with the seat, the initial Atlantis (orange one) is a much more handsome frame, but that has nothing to do with size. the tilting down of the seat on that indicates to me something is not right for you.

If you are going to set up a new unloaded road bike in the same basic position as the others, then my question is why bother. You are not going to get the performance out of that frame anyway.