Think about the features and how you currently use the D200 now. Then put together a checklist of those features to test on the D7100. Check the basics of capturing RAW and JPEG. Make sure you can successfully download to your computer and manipulate in post processing. That should considerably shorten the amount of required testing.
Regarding the "high defect rate" please remember that many more people post when they have an issue than those who have success. Some of those issues are also user error and not the camera.
Use the D7100 every day until you leave. Practice will breed familiarity and confidence. You may even elect to leave the D200 at home.
"Red is gray and yellow white, but we decide which is right ....and which is an illusion"