I have Cubase 6, Reason 5 and Ableton Live 8 and they all seem to have their strengths and weaknesses (I'm not trying to start another DAW wars discussion
Cubase - Awesome sequencer and love how you can customize everything. I particularly like being able to set up hotkeys because it minimizes mouse clicks in addition to exponentially speed up my workflow
Ableton - I find the Drum Rack in Ableton is second to none. It's fast and the GUI and flow is just amazing. Love the fact that you can attach plugins to pretty much anything simply by clicking and dragging it over any drum rack pad.
Reason - I grew up with Reason. I know all the instruments very intimately and love everything about Reason, but I found the sequencer slightly more cumbersome than Cubase.
The other day, I opened up Cubase, then live and everything worked great. Then by mistake, I click on Reason and what happened next was unexpected, it worked. I expected some error message to pop up but all three seemed fine and not only that, Live and Reason both seem to rewire as slaves to Cubase (host).
My question is, has anyone else tried this configuration with using Cubase, Live and Reason all at the same time? If so, did it work for you as well? Any issues? Let's also assume that latency and CPU is not an issue when running all three.