If you have only one day and are bursting with energy and desire, go for it. You'll see the scenery. You might even attain a greater sense of physical accomplishment. Visitors rarely get to know a place as well as residents. Dayhikers are visitors.
Backpackers are temporary residents.
We recommend starting the loop by hiking up the North Fork, as described here, because you can ease into it this way, rather than immediately grinding straight up to Round Lake and flinging yourself at the mercy of Lost Creek Ridge. The trees are so tall it's hard to look at them while carrying a big pack. For a shoulder-season dayhike, keep in mind this section along the North Fork, between the trailhead and McKinaw Shelter. It passes through an exceptionally grand ancient forest. Then there's the view from Red Pass.