I have never needed multicam -- so a while ago I manufactured a situation to see how it works in FCP 7 and FCP X (I couldn't find any tutorials that include multicam footage, so I created some using 3 different cameras).
Anyway, I experimented and found that FCP 7 was more flexible -- but you had to do a lot of PITA prep work to get the videos in the proper format and sync method...
FCP X .0.2 seemed easier/faster but was limited to audio sync ala PluralEyes.
I've read comments by pros that audio sync is not acceptable for concerts, large venues, etc. where the camera distance from the subject varies considerably.
Now, FCP X .0.3 has robust multi cam support -- and from what I am reading (and seeing demoed) it is superior to anything else out there!
I wonder if this "robust multi cam" capability is enough justification to use FCP X -- for that capability, alone?
Here's some of the FCP X benes:
-- any combination of [supported] cameras/file formats
-- any combination of [supported] codecs
-- any combination of frame sizes
-- any combination of frames per second
-- photos and still images can be included
-- automatically assemble broken timecodes from each camera and lay out as a single angle
-- sync by timecode
-- sync by the recorded date / time of the camera
-- sync by start of first clip
-- sync by first marker on the angle
-- sync by audio
The audio sync can be used alone or in combination with other sync methods.
Here are some links that show what I mean:FCPX INs and OUTs - Multicam Part ONEFCPX INs and OUTs - Multicam Part TWOMulticam Editing in Final Cut Pro X
Finally, this last tutorial has nothing to do with multicam -- but really blows me away:Advanced Tips for FCP X: Editing During Playback
That's right he is editing in real-time during playback!
He shows how easy it is -- fast, natural and fun!
He says that editing this way is almost like playing a musical instrument..."editing this way is almost like playing a musical instrument..."