I have my master catalog on a Mac, but I often print from a windows workstation.
The photos and the sidecar files are synchronized, so they are not an issue; the problem is usually the catalog:
- in the catalog paths are stored natively, so on the mac we have unix-style paths /.../.../.../ and C:\...\...\ on windows. However annoying, this is not the major problem, because if you have only one root folder when you open a catalog created on a different machine, Lightroom will just tell you that all photos are offline, but you simply point it to wherever the root is and it will update the links.
- I have two different catalogs: even if I have a copy of the mac-catalog on the pc, I usually avoid opening it directly; I prefer to sync the root folder. But some stuff is stored only in the catalog, in particular virtual copies. If you have two different catalogs, they won't appear. Moreover, the path-resync workaround does not typically fix virtual copies, so even if you open the original catalog, you may not be able to use them.