Just this evening our dev team finished importing private messages.
As for why we upgraded when we did, it was partially dictated by our previous hosting company. The other reason is that we are now self-hosting, which allows us to fix things more quickly. I know that might not seem true given the time it took to get private messages back, but it really is true. In the past we’ve had much smaller problems take months to fix. As our team learns the new system, we’ll be able to do things more quickly here.