I am not active or non member here, and no experienced, but i like to share anyhow which is not harmful i hope.
I have Sppyder3Studio, i don't know if that is working or not, as i said i am not expert or pro to see if i did a great job, maybe to my eyes it is perfect but for others it is not good enough, anyway, i use it and all my prints are amazing out of printer, no one print is off or bad, and all the shots on the monitor are great as well, i sent few of my photos to different places and i saw the prints, all came out fine and stunning, so i can finalize my judgment that Spyder3 working perfect on my MacBook Pro, and really i don't know what another calibration device will do more that that, i even didn't use that Spyder3Print coming along with [included] with Spyder3Studio, the prints are really terrific and no need to calibrate the printer [Epson 3800], so i should test this device on another monitor and another printer and see if that will work as well or not.