I have Octalink LX on my steel tourer and kind of regret it. They work just fine but it was interim technology and the lifespan of the BB is not that good. The spindle is much stiffer but I dont need that. The bearings are much smaller and wear faster and I dont need that either.
Once Shimano transition everything to external bearings they will cease production of the Octalink BB units and in 10 years time they will be hard to find.
Even the external BB design is transitional, till "the industry" decide on a standard larger diameter BB shell, then everything can go back inside the shell, where it properly belongs. It seems daft moving the headset bearings from external to internal and the BB bearings from internal to external.
Square taper is already obscelete but niche companies (Phill Woods, TA to name but 2) produce fine BB units in most sizes.