There won’t be a difference in the capabilities in Alarm.com rules between the systems. Newer devices will be supported by the IQ Panel, and a lot of integration benefits exist like Alarm.com scenes on the panel, video streaming on the panel, MyQ Garage control on the panel. Z-wave rules in Alarm.com won’t really be impacted.
The IQ Panel 4 has the option to pair Z-wave controllers. The UI is identical to the IQ Panel 2+ so you can find details here.