Does not appear to be any difference in specs. After renting Speedblade, I nearly bought them until realizing that they are same club as RocketBladez, apparently intended to capture the lower level (75) market so players don't have to wait till level 79 to spend their money on the same club-- yellow decorations on the club vs. blue decorations.
Have not rented the RocketBladez because I expect that it would not reveal more than the obvious already observed and experienced. Does anyone have any experience using both of these sets? Apparently players have test marketed pre-release Speedblades, evidenced by the date of the reviews appearing before the clubs were released. Maybe someone who used both the RocketBlades and Speedblades might comment?