Square taper bottom bracket - new UN300 or old style UN55?

[NHAero]

Shimano square taper BBs have always been bombproof for me. I learned that the UN55 is discontinued and the replacement is UN300. The new one is less expensive, so I wonder if it's also less good. It's not like a UN55 is gonna break the bank if I find one.

Any input on how they compare?