The SPL De-Esser is very nice and quite transparent for general vocal, guitars...etc mixing. I have the Sonnox SuprEsser and Antares Avox Sybil too, but the SPL is kind of set and forget, too easy and fast to dial-in the proper amount of de-essing.
The Sonnox SuprEsser is the best for more advanced and picky de-essing & de-harshing.