Ditto what the general concensus here says. I have many many red leg scarlett hermits in my tank. I only bought those because of the nightmare stories I hear about blue legs and others.
So far my scarletts have been a great in my tank. They have yet to kill anything, including each other and snails. I keep some spare shells lying around the DSB so they have a home readily available.
I hear bluelegs fight with each other, kill snails, and just are nasty little buggers.
As far as scarletts and doing their job as a cleanup crew, I have no complaints. I see them everywhere in the tank, including on the DSB sometimes. They are amazing algae eaters, and detritus eaters. Just seem like good all around assets to me. I plan on buying more.