You may see some different line breaks, depending on how tight your layout is and how large the copy blocks are. If you're one of those folks who applies lots of little tricks to adjust your copyfit in documents — I am not trying to point a finger here; I stand before you guilty as charged — those fixes may stand out and need to be modified as they're found.
If you'd ask me what you want to do, which maybe you have, maybe you haven't, I would do it on a case-by-case basis as I needed to do it. Because you're right: if you're a detail-oriented person with a big bag of tricks, this can, on occasion, be a big pain. If the trip isn't necessary, there's no need to go down that road.
- First I'd run a PDF of the existing document, preferably before the currently two year out end-of-support for Type 1 fonts. It gives you the baseline you want, and into the future if you want to re-use the document with no changes it gives you a file where the end-of-life of Type 1 fonts won't apply. If you just need to recycle/reproduce the job you've got, save yourself the effort and work from the preserved-state PDF.
- Then I'd open the document and start proofing pages. Primarily you're looking for line breaks, fixes which may have turned into gaps in the copy block, and spots where a formerly perfect cheat turns into layout issues.
- If there only a few issues, which will generally be the case, all you have to do is hunt them down and fix them.
- If there are a bunch, I'd recommend that you first set all the type back to the style baselines — kill changes based on the style. It's the only way to be sure. That's a lot easier to do, of course, if you made changes based on character styles, not so much if you just set type to be bold, italic, bold italic and/or underlined on the fly. Then, if needed, re-apply your magic fixes for tailoring the document(s) to your standards. Again, this is where that intrinsic PDF with how the document used to be will be your guide.
It stinks to realize this. But the more exacting your standards are, and the more skilled you are in using a variety of tools and tricks to bend InDesign copyfit to your will, the more attention you'll need to apply to make the transition seem seamless. Of course you'll know it's not. But if you do what's needed, at least there will be no evidence at the scene of the crime.
For better or worse, I hope this helps.
Randy