Honestly, if your sites are already built in Webflow with no issues then I wouldn't bother migrating over to Framer. I don't see the benefit unless you're building custom React components to slot into a Framer version. Webflow is just as powerful if not more so. And that's coming from me using Framer, not Webflow, and being a total fanboy.
I'd just build new sites in Framer if you want to move away from it for your own design/build ease, or other personal reasons. No need to put yourself through the hassle of migrating everything unless you need to for some reason.