it's a good idea unless there's a performance hit to turn it on for JPEG output.
That's what I'm currently doing. A few months ago I decided to quit using RAW for personal stuff, preferring final exposures in-camera. I'm shooting medium quality, max resolution jpegs with DLO and ALO.
It's not that I'm taking much advantage of DLO, as in fact I dial down sharpness a little but, I when I tested the 45mm, I noticed that DLO also cleared residual spherical aberrations, and that lead me to give it a try with all lenses.
Depends on the correction - does stretching qualify as correction?
That's the thing, yes. Even if being done optically, it's still stretching. Some defend adding, for instance, an extra lens element to straighten the image.
Will that extra element lead to a softer image? Perhaps.
Will that optically corrected image be softer than cropping a few pixels and enlarging a little bit? Hmm maybe, we don't really know.
Two things are certain:
1. The uncorrected image is the sharpest.
2. Profile corrections can be improved with new algorithms, for the same existing lenses, via lens firmware, new DLO methods or updates to post-processing software, while optical corrections stay the same for the lens lifetime.