Bontrager XXX Lite 1,75-2,35" - weights about 95g, using them very short, but alot better than Maxxis Ultralight's with 130g. My friend using them (Bontrager's) a lot longer and is very satisfied. Apart being a retro and WW, I ride more like retro - where the mtb is designed for. My weight is about 95kg, so not an easy life for light tubes.
Very important is to have good tire pressure - little more than with heavier tubes, because the light ones are more prone to snakebites, when the pressure is bit too low. Besides they loose air a little through these thin walls - not much, needs some pumping one a week.
Reliable yes, but need more attention to tire pressure.
Cheers
therapy