I disagree with you on the "gutiarists make better bassists than bassists make guitarists" thing. Most times I've ever seen a guitarist pick up a bass, he make it sound like crap. Fret buzz left and right, attempting to play chords, terribly timing, etc. Most bassists have at least a basic understanding of music theory and can at least play a basic guitar part. That is my experience, anyway.
I know what you mean. I recently played a gig with this band who I think have split up now. Their lead guitarist is incredible - imagine a cross between John Petrucci, Vai and Claudio Sanchez in playing style and you'll know what I mean. Anyways, for one song he swapped instruments with the bassist, plays this awesome little tapping solo and then proceeds to play root notes for the rest of the next song. I spent the rest of the gig with my mouth hanging completely open. What a waste of talent.
But yeah, even when rocking out with TEH SHREDDORZZ!!! he just looked awkward, which was unfortunate.
