The X10 outlet has a mechanical ratchet switch in it and toggles between on and off. Thus the CLUNK. Same for the X10 WS13 wall switch.
I don’t have an OutletLinc but if it is like the ApplianceLinc and Switchlinc Relay modules; they uses a power relay and not a mechanical ratchet switch. It will be much quieter.
I am sure someone with an OutletLinc will verify this for you.
Remember Insteon Devices are two way so as you add Insteon devices the remaining X10 ones may start missing things. Two way modules can absorb signals and Insteon does not rebroadcast X10 messages only Insteon ones.