I just replaced a set of Schwalbe One V-Guards in 700x23 with a set of Continental Ultra Sport II in 700x25.

The Contis definitely are not faster, especially on smooth pavement. I'd say the Rolling Resistance site's review for both tires are accurate.

In terms of handling, the wider Contis feel squirrely on fast turns. No idea whether that's a characteristic of the Ultra Sport II, but I suspect it's more due to squeezing wider tires into narrow rims. My bike's Araya CTL-370 rims have an inner width of 14mm or 14.5mm and the bike was originally fitted with 700x18 tires. The Schwalbe Ones in 700x23 handled great, tracking curves like they were on rails. But 700x25 may be pushing the optimal handling limits. Not a big deal since I don't race and don't anticipate needing to take turns fast.

The wider Contis feel much plusher where it counts, on chip seal and bad pavement. If I can put more energy into forward motion rather into absorbing road chatter, that's a good thing overall. The main hindrance I found last year was riding farther than 30 miles. After that point neck pain from an old C2 injury overwhelmed everything else. So it'll be interesting to see how the softer riding Contis feel over distance.

Too soon to say whether the wider Contis might be more efficient overall, and not simply more comfortable. I still haven't regained my strength from a month-long bout with flu.

And the weather hasn't been ideal for comparing familiar segments with my best times from last year on the excellent Schwalbe Ones. I've beaten some of my best times recently riding the wider Contis, but those aren't really comparable -- they were heavily wind assisted, both climbing and downhill as the wind has shifted between strong south and strong north winds. It's possible under similar conditions the Schwalbes would have turned in even faster times. I just didn't have the advantage of that much wind assist last year with the Schwalbe Ones, since our peak wind assist season is late winter/early spring to mid or late spring.