Flexible sensing styluses deliver additional degrees of input for pen-based interaction, yet no research on bendable styluses has looked at the influence of stiffness on performance or its integration with creative digital applications. We conducted two experiments that evaluated the influence of flexural stiffness on users' performance. To address this, we designed HyperBrush a flexible sensing stylus with interchangeable flexible components. We assessed the performance of different flexibilities on a bend menu technique. While bend input in styluses can perform similarly to pressure input, researchers only have measured stationary input. We furthered this discussion by evaluating performance of simultaneous bend and X-Y pen movement. We conducted a third experiment that investigated how HyperBrush can be a beneficial tool to support users' creativity for digital drawing. We concluded that different flexibilities can pose their own unique advantages analogous to an artist's assortment of paintbrushes.