Krakow to Budapest - night train?

[Toofarfromthesea]

We are booked on a Viking Christmas market cruise this December with a planned 5 night pre-cruise stay in Krakow that we are organizing on our own. But now, in the interest of a new experience, I am thinking about cutting that short one night in favor of a sleeper compartment on the night train to Budapest. That would get us to Budapest the morning of the day we go aboard, but the boat then doesn't leave Budapest until the following day.

 

The train fare would be a wash with one less night at the hotel, but we would save the not inconsiderable cost of the car I had booked (not yet paid for, and cancellable) to transfer us from Krakow to Budapest.

 

Has anyone had any experience with this, or similar night trains in Central Europe? I've traveled in a first class train compartment in Europe but never a sleeper. My personal guideline of, 'if not now, when?' makes it an attractive alternative.

 

Thanks for any advice, warnings, or suggestions anyone can offer.