It would be good o be able to save and load non-disk based styles
Where do you want to save/load them from/to?
Into a database?
Not necessarily, a mwlayer file same as shp will be good. It takes time to set labels, colors... so you don't want to loose them.
Do you mean something like this:
Could be, even if I think that it would be good to have all working the same.
So far it seems that this feature does not work for postgis because save style shows nothing and open folder returns an error.
I suggest that message "can not save the settings for a non-disk based layer" (happening with a right click in legend)
be completed then with "use layer properties save style"