Seriously though, there should be a method to accurately record from a DAW such as Renoise. I know it is possible. The way I get a perfectly maintained BPM is that I give the DAW (Renoise) enough patterns to cover the length of the song. Then I hit “render file to disk in realtime,” which starts to play the pattern and record on the DAW. With trained reflexes, I hit the play button on my synced machines (impossible to hit perfectly) then wait for the patterns to end and hit the stop render button on the DAW. This is a very stupid method that I only use because it can at least record the song, though imperfectly timed.
If I could have Renoise sync the start-stops with my Elektron gear so that a DAW rendering starts the Renoise pattern as well as the external synths, then my problem would be solved. You cannot use Renoise as a MIDI master and a slave at the same time, or else this might sync the start/stops. Anyways, there should be a way to record with the DAW as a MIDI slave to the machines, with the recording starting only when you hit play on the machine. That would also solve my problem. But it seems the answers I seek are out of reach at the moment.