Automating Parameters on Hardware

So I'm leaning towards getting some hardware synths, but I like my ability to automate parameters (cutoff, attack, etc) with soft synths.

I want to know how easy/difficult it is to do this on hardware. I'm assuming it can be done through CC messages at least.

Yes it can be done with CC Messages, as long as the hardware supports it. I have an Alpha Juno 1 that doesn't respond to CC, but it does respond to Sysex, but Sysex is much more inefficient in that respect.

Most smart analog synths today should work instantly with CC messages. All I had to do is connect the MIDI out of my interface into the voyager's MIDI in and they were talking like old friends. Perhaps you could even interface with all analog synths using MOTU's volta, a computer controlled control voltage plugin.