A UN-5x is around 300g while a UN-7x is around 250g a UN91 is claimed to be about 220...

I put a phil wood Ti-magnum BB on my road bike with my 185mm TA Carmina cranks to save weight. With the alloy cups it's under 150g. So pretty significan't weight savings if you are a weenie. And I was trying to get my steel road bike (carbon fork) down to 17lbs in an XL size. I eventually succeeded, but with a dura-ace 7800 180mm crank-set. I still use the TA's and my classic lugged, road bike with fenders though. That is a for life crank and BB set.