The reality is, that he and Power are contemporaries, whether you want to believe that or not. If you want to add in similar top 10 profiled defensemen of recent years, Sanderson and Seider would be the two logical additions. All of these guys possess prototypical size or greater. Are at a minimum, a plus skater for their size. Handle the defensive zone well, defend and initiate transition well, think the game at a high level, and have a largely unknown offensive upside at the NHL level. At varying levels they all excel at pretty much every aspect of their position. You could spend all of eternity arguing which prospect was best at which category. They are big bodies, will take on the hardest assignments for their teams, their impact will be noticed most from the D zone out.
Drysdale/Hughes/Byram/Clarke, to me, represent a different style of defenseman. They certainly have a place in the overall discussion.
This game of breaking down ceilings and floors is always going to be swayed based on personal perception of the player. My original comment of him having a higher floor than many top D prospects reflects this to a certain extent, but beating the dead horse that Edvinsson's floor is the lowest is just kind of... pointless. Edvinsson would not drown playing in the NHL today. It wouldn't be best for his development and there would be some bumps in the process, but I believe he could keep up with play today. Edvinsson's supposed low floor is that of a guy who will likely crack the opening night roster in Detroit next year and have a chance at a long NHL career, so I have a real hard time believing he has the lowest floor of the top D prospects. Unless you are going to tell me that all of these guys are guaranteed to be lock top 4 defensemen.