If I understand correctly, they've retasked the zoom/size button to go to this re-flowed approach rather than the "crop the margins" thing it was doing. If they stick with that arrangement, then I think we'd probably be giving up the latter of those two settings. It occurs to me, however that the Sony developers might remember that there's a third
setting for that button which isn't currently doing anything in PDFs, so there's space in the current control set for both options.
It is also my understanding that this reflow mode simply strips out the images from a PDF and displays the reflowed text, rather like the Reader does with RTF files with inline images, just skipping them. In this case, I'd think that the image-based PDFs you're talking about would be useless with the reflowing, as there's no actual text there to be
reflowed. However, I'd expect the ones that have been sliced-n-diced by an app like PDFLRF would still work as they do now on the non-reflowed setting.
Of course that all assumes that the not-yet finished reflow feature ends up working substantially the way it's currently being reported to work. If it needs to be pointed out, things do have a tendency to change a lot during development.