Latest wisdom on permalinks?

I’ve been hanging back on v2.2 in part because I’ve been afraid that upgrading will cause permalinks to break, thus severing the links from the outside world to my blog. I posted
this forum inquiry but there was never a response. And I see others have had issues with permalinks through the releases, so my confidence in support for this feature is low.

So are permalinks in v2.7 working OK?

With reference to that other thread, is there any way to ensure that an older permalink or slug will resolve to the proper entry if I change formats moving forward?

Is there any blog or document about caveats related to permalink reorganization?

Thanks!