I would not say they harm a driveline if used correctly.They may not be the best for some conditions.They do cause a heavy wax buildup and IMO there are better lubes. Prolink,triflo and Bioshield are other alternatives.
I'll side with Boudreaux on this one. Waxes work nice and slick and clean for about an hour or until it rains. Prolink is excellent. You might try looking at www.mtbr.com for lube product reviews.