First of all, I can understand your frustration. More advanced audio routing is something that has been discussed quite a bit here on the forums, so we do understand that it’s a desirable feature. I’m pretty sure that it will be addressed at some point in the future, but at the moment it is not possible.
Second of all, it’s important to understand that sidechaining and audio routing are separate concepts. Sidechaining is simply a technique to convert an audio signal into a control signal for something else. It’s obviously very commonly used to control compression levels, but it can also apply to many other effects and situations. However, when connecting the Signal Follower device to a Gainer or Compressor (or various other devices), it is actually possible to perform your own sidechain compression techniques and do popular things like ‘ducking’ the volume of a bassline when the kick hits. But ultimately the Signal Follower is a meta device, so it cannot perform any audio routing; it can only control the parameters of other devices.
If this issue of audio routing was such a critical part of your workflow and something that can ‘make or break’ the software for you, then this should have been the first thing to test in the Renoise demo. This is why we do not place any major restrictions on the demo - so that people can fully test things and make sure that it works the way they expect.
Anyway… Hopefully this is not the end of the Renoise world for you. All DAWs have their pros and cons, their own unique characteristics and behaviours, etc. Try to think about all the awesome things that Renoise can do, rather than focusing on a few negative aspects.