I am new to the smart controllers but have a quick question. I currently have 6 zones but found the best deal on a 12 zone control panel. Is there any downside to using the 12 vs the 8 zone? I would expect there is not, but wanted to get a few opinion.
I have 8 zones and picked up the 12 zone model from Costco. When setting up you don’t activate the unneeded zones but have them if needed in the future. Highly recommend!
No downside. In fact only upside imho. What if you want to add a zone someday? 
@DMXS - the other thing you can do with the extra zones is to set up a phantom system, if you want to see how different settings would so - say Fixed vs. Flex. One doesn’t have to actually connect a solenoid to the system.