Hi Donna, We have cycled the Danube on 4 occasions, all self-guided trips. It was wonderful! While we planned our own trips, we have run into people that used https://en.radreisen.at/. They seemed to be very pleased with them. Good service, etc. We don’t have any experience with the other two companies you mentioned. We also would recommend this company based out of England. While we didn’t use them, the people we met who did raved about them. https://www.freedomtreks.co.uk/ Had we decided to use a tour company this would have been our choice.
We have also done seminars for REI at their stores about a dozen times. We aren’t selling anything, just trying to get people excited about cycling in Europe. Two things you might consider if you haven’t already. We have met people who do the bike and boat thing. The plus side of that, you check into one room and unpack only once. The downside is you eat breakfast and dinner in the same place every day. The food will be good. But you miss the opportunity for many different cultural experiences along the way by staying in different hotels. It sounds like you are planning on different hotels…good for you.
When looking at tour companies, many of them keep their cost down by staying in the area rather than right in town. Example, “staying in the Linz area” instead of “staying in Linz”. While it sounds like a subtle difference, it often means you are 5 miles out of town. So if you rode your bike into town for dinner you have to ride back to your lodging. You miss opportunities to walk around the small towns along the way.
Feel free to contact us with a PM. We would be happy to share with you our REI handouts and chat. Looks like we are almost neighbors! Jane and Jim