Nicely designed,” the Massey De:Esser “sounds great and has revolutionary features,” while being “a deeper plug-in than you might expect from a de-esser.

De:Esser is silky smooth and cleanly limits sibilance while leaving the "voiced" portion of your vocals unscathed. It “stays out of the way – while getting the job done.”  The dynamic threshold algorithm ensures perfect reduction regardless of perceptual loudness or dynamics in the vocal performance.

I don't think you can find a better RTAS/TDM De-Esser