I have both RR and LR. The RR is great for brush, vines and saplings. It tears it out easily and allows for piling the trash, etc. I also use it for my gravel driveway, but to touch up small holes and ruts between use of a boxblade. If I need the boxblade to have more gravel to work with, however, I just put the scarifiers down and it works perfectly. Usually I need do nothing.
The RR is also great in pulling out vines in pasture too low for a rotary cutter, and for tearing out sod for a seedbed. It's also great to have the implement in front of you and not, like the LR, behind where you can't watch it closely.
The LR is of little use in brush because it does load up quickly and is hard to empty. Trying to pull brush with it is also taking a risk of bending tines or the rake itself when you hit a bigger sapling or stump. I use the LR several times a year to pull gravel back into my mile long gravel drive. My blade pulls in lots of dirt and trash when I do that. The LR, however, brings only a little bit of trash in and it usually blows away quickly. The LR also pulls out the random larger stone that surfaces in the drive sometimes. And it is good for pulling rocks out of a garden or just soil.