I race on Tufos
http://www.tufonorthamerica.com/tire...hp?seriesid=26 and Specialized Mondo. Tufo has an interesting technology. It uses a Butyl tube that holds pressure over a long period of time and can be used in combination with the Tufo Sealer. If a piece of glass punctures the tire, the sealer reseals the tubular tire with a resulting slight loss of pressure. Also, Tufo makes tape that can be used to mount and secure the tires on the rims.
Many other manufacturers use latex tubes which allow the slow leakage of air and cannot accommodate sealant.
Which is better? Well, we can start a comparison war between riders / racers who swear by both systems. The Tufos theoretically have greater rolling resistance and are not as supple. However, you do get to the finish line. Latex tubes theoretically have lower rolling resistance and a better ride. So, some riders / racers feel they are faster on latex tubes. Hopefully, they get to the finish line.
At the track, most racers use tubulars and glue the tires on the rims. The tape is not strong enough for most of the track events.
LBSs are all over the map on advice / support for tubular tires. They charge a lot for mounting and removal of the tires and the tires are expensive. The shop I use carries a large selection of tubulars and supports / promotes their use.
Are they worth it? Well, there is a significant body of evidence in bike tech review showing that clinchers with latex tubes have lower rolling resistance than tubulars which trumps any weight savings. However, races are not won in the laboratory but on the road with varying conditions. If a racer thinks he / she can win with a particular tire then that is the one that will work the best.
I go back to my initial point which is you have to finish to win. I prefer a little more robust system and that is why I like Tufos for the road. On the track, I am still considering what tire system makes the most sense.