I actually did this as 2 separate hikes due to some time constraints the first day, should be easily possible as one loop though. Agree with the previous post that if you do it as one loop you should do this from Robson Pass end to get the elevation out the way, if you hike the shorter loop (Hargreaves and Toboggan falls only) then start with Hargreaves lake as this is a rougher terrain and so it's easier to hike up this and then down the easier trail at Toboggan falls. See Hike 1 for Hargreaves lake and Toboggan Falls description.
Hike 2: Mumm Basin and Toboggan Falls.
This hike offers excellent views of Berg Lake, Mist and Berg glaciers, Mount Robson, Robson Glacier, surrounding mountains and Adolphus Lake. Started at the Robson Pass end of the trail and returned via Toboggan Falls route. Enjoyed the hike along the flats between Berg Lake and Robson Pass campground, the junction for the Mumm Basin Route is well signed and the trail is well trodden. Follow the cairns once at the top of the trail across the Basin/alpine area. Beautiful views of Berg Lake. Highly recommend this trail.
Trail is snow-free, few creek crossings but they were easy enough on some well-placed rocks. We made the side trip to the 'cave', not much extra elevation to reach it (took about 10-15 minutes from the junction with the Mumm Basin route). The cave is not very big but interesting anyway, it seems to be formed from an entire rock slab that has fallen/slid rather than being a true cave.
Went back down the Toboggan Falls route which was a repeat of Hike 1. Recommend doing the whole loop (including Hargreaves) so that you see the wild flowers. Mumm Basin itself is very nice and offers the best views of the surrounding glaciers and peaks.
If time allows, take the side trip to Adolphus lake, although the view of the lake is better from Mumm Basin trail, you get to hike into Alberta by hiking to the lake.