I tried tubies for 2K miles last season (DV46 UL and Conty GP4000SR loaded with a bit of no-flat goo), but decided I'm better suited to clinchers. Note than I'm a a recreational rider, not a racer. I'm a certifiable weight weenie.

Pros - I think the tubies handled tight twisties and cornered better / faster. At higher psi's (~120-140psi), the tubies were a smoother ride. However, the advantages of riding at higher psi's seem to be in question. The light weight Reynolds rev'ed up nicely on slower, steeper climbs.

Cons - Flatting out of two big group rides sealed the deal for moving back to clinchers. I looked for a chase car with spares, but nada (ha ha). Both times, my can of Vittoria Pitstop left me high and dry. Ugh. Stan's goo is reportedly better, but neither could be foolproof - right? Riding a non-glued on spare that I "installed" in the field didn't sound good to me, nor did having to pack the damned spare around town. Gluing on new tires guarantees some amount of downtime (more if your LBS does it and less if you do it assuming you have the supplies on-hand). Cost? You're paying $100 for a good tubie if my memory serves correctly plus the installation price if your LBS does it.

As for weight savings, clincher rims / wheels usually can't hold a candle to tubie rims / wheels. However, it's not all bad news because clincher tires (180g/ea) / tubes (55g/ea) / Veloplugs (?g/ea) can be lighter than tubies (270g/ea + a few grams for some no-flat goo). Being a weight weenie, consider the weight of your repair kit: spare tube vs. spare tubie vs. can of goo.

Clinchers - It's such a relief being able to fix my flats out on the road now. Clinchers are capable of cornering faster than I dare. On the same slow, steep climbs I'm still putting in similar overall times.