Same here. For scaling from medium to large fonts the MSDFs were good. However at smaller "normal" font sizes they just didn't tend to look good even with larger MSDF sizes.
Plus for font rendering the GPU overhead was too large to be worthwhile for normal GUI apps. Font atlas'es are pretty small, and most fonts for GUIs are statically sized.
However I did find MSDF are fantastic for rendering complex SVG paths with lots of benefits [1]! You can use a 64x64 SVG star and scale it up fullscreen with reasonable loss in quality [2] (or use 128x128 for almost lossless images).
I use them as the core of my GUI library to render complex SVG paths for icons and such and compose individual paths on the GPU.
You can use them to implement fair chunks of Lottie animation as well [3]. Though I never got enough into the Lottie work to go beyond basic demos, but you could easily scale MSDFs, add shadows, feathering, outlines, etc at 100+ FPS.
1: https://forum.nim-lang.org/t/14062#85314
2: https://github.com/elcritch/figdraw#msdf-bitmap-based-sdf-re...