A very good analysis Cheviot, I echo your conclusions. I love my SpyderRench, but some of the reasons why are very superficial:
1) I like the clever way everything fits together, and enjoy "playing" with it.
2) The quality of manufacture is top-notch.
3) I'm the only kid on my block who has one! (and enjoy the fuss everyone makes when I whip my tool out.

)
That being said, I pack a Leatherman Wave when there's serious work to be done. The SpydeRench is better to carry to neighborhood barbeques or family camping trips, where a simple multi tool chore is more likely to have an appreciative audience.
~Bob