If switching cranks is going to be important for you, keep in mind that you will need a crank puller for the square taper BB, and you will NOT need this for the octalink.

It takes only an extra minute or so to pull the cranks, but it is an extra tool and an extra step.

I doubt 99.9% of us would notice the difference in stiffness between any BB....especially if placed in an 80s steel frame, for which you can SEE the flex of the frame in applying weight to the pedals.