Well it does make the code neater even if it's not a lot faster, so I like it.

As for the question of how common that use case is, it might depend on the software pipeline.  For example, in SDSS if you have a big deblend then most of the constituents will be drawn into postage stamps that are rather large but have the locations of all the other objects masked out.  This means those guys have a lot of masked pixels.  But big deblends are not very common in SDSS because it's shallow.