With Vittoria Latex tubes on sale this spring I ordered four to give 'em a shot. I understand there were some problems with that lot (hence the sale at Nashbar), so my experience may not be typical. Anywho...
Two of 'em never made it out of the garage and blew (seam failure, perhaps) on their own. One is on the front doing just fine and another under the seat as a second spare (they are tiny). The latex one loses about twice the amount of air that a butyl tube does. If you top off the air every day (I do) then it really doesn't matter. As to the ride, I can't tell any difference on my Vittoria Rubino's. I've heard that when used under a high zoot 'open tubular' that they shine quite nicely.