It'd be really cool if there was a way to have LADSPA effects for each specific channel, rather than have them only for the entire audio output or each instrument.
For example, I typically have all drum instruments and samples running through FX Channel 1, and I would like to have a reverb effect on these as a group.
If I wanted to be really advanced, I could also use MIDI controls to cycle through effects on an instrument by linking it up to the channel LED.
You could implement this by adding an "effects" button below the slider on each channel in the FX Mixer.
If people wanted effects on the entire audio output, they could still achieve this by using the effects button underneath the slider for the "main" channel. No reduction in functionality whatsoever.