The problem with this lineup honestly is, as good as the names look on paper, there isn't enough consistent defense. What people fail to realize is GS is an excellent defensive team. Plus, there is only on real facilitator and that's LeBron. Rose, Melo and Bledsoe need to be ball dominant to be effective where GS players get theirs in the flow of the offense.
Series would be fun to watch, but unfortunately, the skill sets that make Melo, D Rose and Bledsoe good players would eventually cancel each other out. No continuity or chemistry with this unit, just names.
LeBron would be back to having to do everything, including having to guard the other team's best player, and as offensively loaded as GS is, that would be a huge problem.