.NET CMS that handle complex surveys

Our customer wants to migrate from **DotNetNuke** to another open source .NET CMS. I'm looking for something that will have the same advantages as **DNN+Dynamic Forms/Registrations** - ie. possibility **to create complex surveys with events** (showing one field based on response from another, auto-submit if specific answer occurs, events on survey submit like SQL query execution, HTTP POST or e-mail sending).
Right now there are thousands **(around 50-100k) active users** (each user logs in and has her/his personal data stored in DNN surveys), so this CMS should be capable of creating rather big solutions.

What are the options? Should we stick to DNN considering migration to a newer version? Are newer DNN versions worth the rework (we're currently running on 4.9.5). **Are there any open source and free .NET CMS-es that are comparable to DNN in terms of survey creation, and are better option when we think of usability, performance, stability, etc.** - basically all the fields where DNN more or less fails? We were thinking of trying out **Umbraco** - does it have a good survey module?

Any suggestions will be much appreciated.

Personally since you have such a platform already built on DNN I would strongly recommend looking at ways to upgrade your current system and stay with it. It will be very hard to find something else that will fit the bill most likely and the migration path will most likely not be smooth.

DNN upgrades can be a bit tedious, but they are not impossible as well as performance and stability are even better with the current versions. Usability is greatly improved with teh 6.x line as well.

Umbraco has a very nice form builder (

[To see links please register here]

) but you have to pay a tiny bit for it - I believe it's 99EUR.

We use it for quite simple surveys/contact us pages etc.

Out of the box it does allow for multi-page surveys (though I've never tried this) but it does not allow conditional questions.

That said it is very simple for users to set up new forms and surveys so I guess it depends how complex your surveys get.