Why is the Ultra-Torque system so much nicer than the square taper setup? Can anyone explain?

This week I got a fantastic Craigslist deal on a used 10-speed Centaur group from a guy who'd upgraded to Super Record. The Ultra-Torque crankset was a compact, though, so I've left my square taper standard 52/39 Chorus crankset on my bike. I'm looking to get a standard 53/39 Ultra-Torque crankset, but I'm confused, as weights of the two setups don't seem much different.

Alloy 10-speed square taper crank setup
Centaur crankset: 700 g
Centaur bottom bracket: 233 g
Total: 933 g

Alloy 10-speed Ultra-Torque crank setup
Centaur crankset: 905 g
Record cups: 49 g
Total: 954 g

The four components I've listed are possibly not all from the same year, but they're from Ribble.co.uk, and are more or less comparable. So am I missing something? I keep reading how Ultra-Torque is so great due to weight savings and better power transmission, but I don't really see the weight savings. So what gives?

(Note: The Centaur UT crankset is given as 905 g, but the supposed less worthy Power Torque crankset is listed at 738 g and costs twice as much. I'm confused.)

I've had both. To me i think that the UT cranksets run a lil bit smoother, but what the big advantage is between the two is maintenance. It's much simpler and requires less tools to take the UT crankset off with pair of hex wrenches and lube the bearings compared to a square tapered crankset. For square taper, you need to extract the crankset, take off the BB and then do some work.

Yep. UT is great for installation and removal. Once they're on you won't notice a difference.

Also,on the external.The bearings are bigger,last longer and make for a stiffer crankset.

You can put 52T and 39T chainrings on your compact if you'd like. TA Nerius rings are here: https://www.peterwhitecycles.com/chainrings.asp

I just got my ultra torque crank last week. I haven't had the chance to put it on yet, but it seems to be light. Pic includes bb cups.

Not so sure about the "stiffer" part - I have a Campy Record 10-speed square-taper crankset on one of my bikes, and I swear that's the stiffest crankset I've ever ridden.

Not that I think it will matter, but fwiw, that 905g Ribble weight seems to be higher than most other quotes. While figures do vary, 856g seems to be the most common for the older silver colored Centaur ST crank.

I like the idea of stiffer. Maybe I will consider getting a UT crank. Ribble seems to have the best prices by far, it's not even close.

Does anybody want to do a trade?