The other name for this approach is the Harwood Trail. Though the hike matches the gain of the Ski Hut route, it's about a mile shorter. But the section from where the trail forks off the Ski Hut Trail to where it meets up with the Devil's Backbone Trail climbs 2500' in one mile!
Its steepness is why, though shorter, this route is really no faster. It is, however, one of the prettiest ways up Baldy. Additional note: the beginning of this trail is much more pronounced and obvious than it used to be.
I've descended Register Ridge twice, and each time I made the same mistake: I left the Devil's Backbone trail too early and wound up traversing steep, loose, and generally unpleasant (even in retrospect) terrain. The first time I never made it all the way over to the ridge and simply descended a miserable gully until I landed in a dustheap on the Ski Hut trail. The second time I traversed a surprisingly (and again, unpleasantly) long way until finally intersecting Register Ridge. I couldn't believe how far over it actually was.
Since I have botched the descent twice (making the same exact mistake each time), I do not know the best place to leave the Devil's Backbone trail. Instead, I would recommend being very careful about not leaving the trail until you are actually on Register Ridge proper.