I should probably add my voice to this thread. Nigel was my first bass hero after starting to play the bass guitar 3 years ago.
My musical background is percussion and voice. I have a bachelor's degree in music education, and I tought public school for a while. So my personal areas of performance are more classical. That affects how I listen to the things Nigel has done.
Three years ago when I started to play, I didn't know who he was at all. I'd only heard of SE as a name of some band that Neil and Tim were in before Crowded House, but I had never heard any Split Enz music at all. A few months after that, toward the end of 2005, I finally heard the music and I was astounded.
When I listened to music before becoming a bassist myself, I heard the gestalt of music, but I never isolated bass parts. Sometimes they were even hard for me to hear. Once I got to Split Enz after having bass under my belt (so to speak) for a few months, I could really and truly hear what Nigel was doing. Again, I was just amazed. His parts were interesting and creative but without gratuitious conceit that would end up as music wankery that didn't serve the song.
One of my favorites of his, already mentioned, is "Giant Heartbeat." Specifically, I love the descending line introduction at the beginning that starts around the 12th fret. It adds energy to the piece of music. I'd heard the same thing done in the choral piece "The Eyes of All Wait Upon Thee" by the composer Jean Berger. In that, the top voices of the ensemble have static chords while the basses rise and fall with the introductory melody. The similarity of this rock song and that classical piece struck in my mind as way cool. By the way, this 12th fret/octave energy is also used by other excellent bassists such as Donald "Duck" Dunn in the Stax great "Knock on Wood" by Eddie Floyd.
Changing meter? Love that, too, perhaps especially because of my percussion background. (I still play in an orchestra.) I had some great fun doing changing meter on some Chavez (Mexican composer) and Stravinsky pieces. We've got that coming back again in several of the Split Enz songs, and it sounds great around the Time and Tide era.
Technique-wise, I noticed he's got a fluid left hand. The movements seem graceful and effortless as if it just flows all over the neck and fingerboard. His right hand is very still, which has been a puzzle to me, but according ot the man himself it's to have an even attack. (I personally play with fingers as opposed to a pick/plectrum that Nigel uses.)
But as far as a groove, locking it in and sounding good? Yeah... he's got it. No one can beat "Dirty Creature" which would be the song I'd nominate to introduce complete strangers to the band. Plus, the first time I heard "Famous People" (not on the A&M release of Frenzy) I must have drooled a little because that song full of sexy, slinky, basstastic goodness.
So... yeah. I appreciate his professional body of work.