Has anyone taken this train recently? We are thinking of buying a double sleeper compartment or perhaps a couchette. I would apreciate any help including booking and purchase options. Thank You.

I did the reverse trip (Munich to Paris) a couple of years ago. I've never been in a double sleeper, but I can tell you all about couchettes. (I don't know how familiar you are with night trains, so if you already know all of the following, please excuse me.) There are six couchettes in each car---stacked three up on either side of a tiny aisle. Try to book the lowest bunk. What people usually do is stuff their luggage under the bottom bed or on a rack near the ceiling. Wear really comfy clothes and sleep in them. Also bring a snack, because you might not feel like eating the train food. I've gone on a lot of night trains by myself, and always found that it was the only time I could really practice my language skills and meet locals; I've always gotten lucky and had super nice, pretty much always polite people who are ready to chat or not chat, depending on what mood you're giving off. It isn't the most comfortable (the beds are kind of narrow), so if you don't think you can fall asleep on a pretty narrow bed, maybe it's worth getting a double sleeper. But I think it's such a fun adventure.

Both sncf.fr and bahn.de will sell you tickets. I think bahn will mail them to you before your trip, but I don't think sncf will mail them to the states (I might be wrong, though). Depending on when you're going, I don't think you need to book the tickets way in advance. Depending on how long you'll be in Paris before going to Munich, you can buy tickets on your first day in Paris at any train station, or at sncf boutiques around the city.

Hope that helps!