I have not been up or down Rose Garden completely, but everything "technical" in Moab is getting really difficult because of buggies and sxs's tearing it up... I do believe Rose Garden Hill is now in that category. It's also not a terribly scenic section compared to the alternatives, but does make a connection that has no short alternatives...
When are you planning to go? You might ask for more recent experiences nearer your trip...
If you end up opting out, you can still run all but that section, and see some great scenery... When you cross the river at Dewey Bridge, the Kokopelli takes you up Entrada Bluffs road, past the Top of the World trail, and eventually down to Rose Garden Hill. The drive up to where the "trail" breaks off the road is fairly scenic, and just a gravel road. Instead of taking the trail when it breaks off (actually the trail continues straight off a hard left in the road...) which gets tight and bumpy taking you to Rose Garden Hill, if you stay on the road it takes you down to a really awesome overlook of the Dolores, which is a nice place to spend the night.
In the morning, double back down the gravel to Dewey Bridge, catch the pavement toward Moab for a few miles, and go up Onion Creek Rd to hook back into the Kokopelli after Rose Garden. If it's not spring, there is a side loop off Entrada Blulffs that crosses the Dolores twice on the way out, but during spring runoff, it's not usually advised, as the Dolores can be up to 5' deep instead of the usual 1-2'.
Onion Creek is a really neat road, with some awesome scenery. I believe the Kokopelli is fairly tame other than the section that takes you down Rose Garden Hill.
Have a good trip!! The Moab area is full of awesome routes, so let me know if you would like a few other recommendations.