The only "downside" is that they reduced the number of Rabbits you could slaughter to incur the Wrath of the Killer Bunny in DKS... I saw a few bunnies at the Orobas Ruins in ED, but not so in DKS.
i remember getting slaughtered by the lvl 21 imps in Orobas Fjords in ED- though, they were much more managable in DKS.
another main difference, mainly for the Xbox 360 version- the inclusion of the Flame of Vengeance afterstory quest.
