I have square taper on two road bikes (old Suntour on one, White Industries titanium BB with old school Dura Ace crankset on another), and BB30 with Ultegra Hollowtech on a third. Any difference I think I feel is due to the frame, not the bottom bracket. It doesn't translate to better performance for me. I'm not strong enough or fast enough, and we don't have any real mountains where some slight differences might matter.

Strong, heavy sprinters might notice some difference in stiffness of the BB and stiffer cranksets. I can't. My "sprints" are a pro's "loafing along in the grupetto" power.

But the swap is pretty easy. RJ the Bike Guy has an excellent video tutorial on YouTube.