I also think Dweller are right. It seems that ARC have a development strategy with module solutions. My guess is that we soon can see a Ref PH8 (PH7 with the "new" power supply and?) CD5's DAC is technical better but many still prefer CD7. My guess is that CD8 is the best of both.
Next major upgrade of Ref3 show the future. ARC's strategy is little tireing. DCS for example have another customer care philosophy with free software upgrades for longer lifecycles.