Despite the name and the gouging rates, this hotel is nowhere near the Messe. This morning they were not able to get me a taxi. I would strongly recommend staying somewhere near the S-Bahn if you want to get to the Messe and back most easily during big events like Electronica.
With “Messe” in the title and the rates they charge they should lay on a shuttle bus. If they did that, the hotel would be an OK option.