Much of what you described as differences fall under the differences I pointed out. As far as not having as much control over who's in your party, that isn't going to affect anyone who doesn't want to use it anymore than it does now on the dungeons people are running that ARE in the DF.
I'm not sure how making it easier to get -into- a dungeon is going to allow people to abuse it for speed running and getting loot faster... In the end, the random assortment of players is only going to hinder attempts at speed runs, and I'm not sure why putting BC in the DF would also mean no lock-outs... As for being able to run the dungeon as many times as you want to practice, you could trade out the weekly lockout for just loot lockouts, so that repeat attempts yield no additional loot.
It's the same argument I've seen with people trying to speedrun AK with DF pugs... The DF was designed to get INTO dungeons faster, it has no bearing on how easy or quickly that dungeon is completed. Difficulty in finding a group for a dungeon doesn't equate to part of that dungeon's difficulty...