I agree with Chris–when I hear clicking or squeaking, if I remove my BB, clean the threads, re-grease, and re-insert, that usually silences the drive train (I also grease the body of the bottom bracket). I don’t think it has anything to do with the axle type. (Note–this experience has been with inboard BBs only)
My experience with outboard has been generally good (I rode it for about a year, then got rid of the bike). I’ve been using a square taper on my commuter for about two years now (middle of the road Shimano model), and besides the basic maintenance outlined above, I’ve had to problems. I also consider the BB in my commuter to be a somewhat disposable item, replaced every 6000 miles or so. If I found two $100 bills in pocket, I’d get a Phil BB and forget about it.
Chris, I’ve heard that the splined Shimano set-ups are being phased out. Is this true?