Honestly, I don't have much. Maybe about 30 members and a ton of informative posts as well as posts between my community that are somewhat worth keeping. But I have done this to them a few times having to re-register for switching between web apps, and I really don't want to put anyone through that again. That is my issue.
I could copy and paste the stuff I need transferred over and deal with it, but I need to keep my members in-tact. I have not found a way to do that and anything I've tried will not give me the correct outcome.