I thought I'd chime in to point out that ALK currently supports MIDI effects. You just use a MIDI track and apply the MIDI plugins -- e.g. Cthulhu. Indeed that the manual is unfortunately out-of-date for this (I'll fix this soon!). The behaviour is now that Instrument tracks do not support MIDI FX anymore (just like Ableton), whereas now MIDI tracks do support (MIDI) effects. If you want to use MIDI FX on an instrument track, you simply create an extra MIDI track, apply MIDI FX there, and then route into the desired Instrument track, taking care to set auditioning to "always on" to ensure the signal flows, no matter what. By the way, another undocumented feature is the ability to output to MIDI hardware. So you can not only use MIDI controllers, you can also send messages -- including sysex (which Ableton doesn't handle) -- to hardware.
With regard to multi-VST output... I sympathise with the notion that this a significant drawback for pros. This is on the list of things I want to implement, and indeed our audio engine most definitely has support for this feature. However, it was a case of choosing a UI design that was simpler which I opted for in interest of shipping. So just to say this is definitely on our radar!
It sounds like you have a really interesting rig, by the way Thanks for you interest and kind words regarding ALK!