DMX is good for theaters and the like but have a look at DALI as well. DALI does groups, scenes and dimming but is costly per light. However with LED lighting taking over, it has had a revival with DALI drivers for LED downlights (typically constant current devices) and LED strips 12/24V (constant Voltage) now available. 0-10V is a fairly simplistic technology and therefore somewhat limited.
Cost is clearly a driving factor but replacing your Halogens with LEDs could reduce your 600 Watts or so to say 120W for the LEDs, it may make sense long term. Especially if you have individual control of every light and dim them to say 50% - that's 60Watts. Plus the saving on cooling in summer. Should I mention climate change as well?