I dont know about the stability. Presumably less so, I haven't made any kind of testing into stability. If I can find that particular piece of film again I'll check it out.
If I were to guess, I would say it's better than with E-6 films and a CD-4 developer, I'm sure I've had a slide I processed in whatever first dev I had at the time, and used the C-41 process from the colour dev step instead of E-6, after returning to the slide, I found it quite dull and poor looking, I think it degraded in a short period (~12 months). I dont remember that kind of thing happening to the C-41 reversed films. Though these films have dye stabiliser built in which may or may not help, I'm sure I used a formalin based stabilising bath for both films though anyway.
It was digitally balanced with levels, the integral mask is still there, however it is somehow balanced well enough against it, that it's not particularly noticeable by eye too much on a light table comparatively to any other neg I've reversed, it's the best looking C-41 film to reversal I've done imo.
In regards to B&W dev pre-treatment... if I were to try this, my starting point would be very weak, as in, you don't want a visible developed negative, but rather amplification of the latent image, but not to the extent of visibly.
Think of SLIMT (selective latent image manipulation technique) vs a full strength bleach. So, a regular developer would be equivalent to a full strength bleach, you want a developer equivalent to the strength of bleach used for SLIMT. At least imo that's where I would start.
The areas that had some amplification/development, would be like increased exposure in those areas, so you need very little. A visibly developed negative would likely give runaway density real quick I would assume.