Wayne - I've been using the Zeo system since last Sept, ~9 months. It's hard to pin point coloration and growth improvements directly at ZEo. I have changed up other variables such as flow and lighting as well. In my opinion Zeo will help keep your water parameters at 0 for phosphate and nitrates..I would recommend it for this purpose.
Here are somethings you have to keep in mind:
-daily dosing....doesn't take long but you have to do it
-pay a bit more $ every month. I have relatively small 90gal so it's managable (~$30 month)
-clear out some room in your sump..the reactor will take up some space
-remove existing investments if you have any (Phosban, Ozone, Refuge etc)
Depending on how hardcore you are..this might be just the thing for you
But then again there are beautiful tanks out there that are maintained without Zeo.