I would advice you to get the latest units, H7600 or H8000Fw as you will get *MANY* advantages over older units:
– much better A/D – D/A audio converters, with 24bit/up to 96KHz sampling (the 4000 doesn't get there)
-a ton lot more DSP power, from 4 to 12 times the power of a 4000!
-MIDI Virtual Racks!!! These alone are worth the purchase. No MIDI latency on these as you will be able to store ten different tweaks within the same preset and recall them with a single MIDI CC message. These powerful presets are racks assembled with 5 powerful FX machines each. You may want to log on Eventidedotcom to check the Presets Manual; in its very last pages there's a full description of what these beasts can do for you.
all the best