Should we use the depricated scale action?

I need the functionality that the "deprecated_scale" action provides, allowing me to scale something down to that one of the dimensions is 50px, then cropping off any extra (50px X 50px). I've tried to recreate this using scale, but it makes sure that BOTH sizes are at the scale size or smaller, so that when i crop, the background shows (black bars).

drewish mentions this here in point 2http://drupal.org/node/371374#comment-1337038, but i didn't see anything tin the docs, google or issue queue (searched "deprecated").

I'm wondering why it is being deprecated, and then what the best practice is to get this functionality.
Cheers