Since I’m a great fan of flexible, versatile, integral applications and also happen to be a Renoise user, I quickly came to the conclusion that Renoise should support wave recording. Renoise is very strong in its sample-based tracking possilibities. Indeed, the wave editing features are quite limited, however the in-track use of wav/mp3 samples and the possibility of feeding them to a (potentially) unlimited collection of vst/dsp effects is just wonderfull.
Now I’m sitting here between a bunch of expensive hardware synthesizers and finding no ways to make them (directly) part of this great environment called Renoise. Ofcourse there are midi options, however with the absence of sysex support and wave recording it is quite difficult to work with them.
For all of this solutions exist. Even very simple adaptations to the Renoise engine could make this work for me (and many other users). 
An example to elaborate my suggested solution:
Suppose we are working with a Renoise instrument set to a certain bank/patch at a certain midi channel. A certain hardware virtual analog synth is listening to this channel and nicely playing all the notes. However, the sound is not exactly as what you want it to be. Therefore you tweak some knobs and adjust the required parameters on the synth. These changes only exist in the patch-buffer of your hardware-synth and not in Renoise. Since having patches stored in your synth as wel as in Renoise is not convenient (causing inconsistencies and a lot of extra archiving work) this should be different.
*) Add two small buttons to each item in the instrument list in Renoise (displayed top-right) with the respective functionalities: send sysex / retrieve sysex.
When having pressed the ‘send sysex’ button Renoise simply sends the stored (not interpreted; dump) sysex data to the midi channel the instrument is set to. If a bank/patch is specified it can send the data directly to that location in your hardware synth.
When having pressed the ‘receive sysex’ button Renoise simply requests the contents of the patch-buffer in your hardware synth and stores it (without interpreting it).
This way Renoise is integrated with your patch editing and also functions as your patch library for that specific .rns track.
Now we still need the possibility to record audio signals sent by your hardware. Assume there is a bunch of midi data in Renoise track 1: note on/off’s, velocities, possible cc’s etc. When playing the track Renoise sends all this data to your synth. This is the way it currently is and how it has to be. However, the audio signals sent back to your PC can’t be captured by Renoise. One could use an external application and subsequently import the wave files into Renoise, but this destroy the versatile integral application idea. So it is clear that Renoise should be capable of recording this audio signals itself. A possible implementation of this functionality could be:
Considered the midi data in track 1 as explained above it would be ideal if Renoise does the following:
**) Each track has a ‘render’ button. When the user presses this render button Renoise starts playing the track (solo) and thereby sending the midi data in the track and records all incoming audio signals until the user presses a button (space -> stop). Now Renoise adds an instrument reference at the exact pattern/row position the user pressed the ‘render’ button in a user-preselected track. The mentioned reference is made to a newly added instrument (+ sample) in the instrument list.
There are most likely some small issues I have overlooked when thinking out this solution, however in my opinion this would GREATLY enhance Renoise its usability and as a direct result its attractivity to musicians.
Moreover… when these implementations are made, Renoise can be considered an integral audio solution.
I very much appreciate some feedback on these suggestions.
Cheers!
Cyrex