Haven't experienced this
I have a 323 with Raymarine hydraulic autopilot, and have not experienced heavy steering at all. The only "problem" we experienced was getting the system properly bled at the initial installation. It took awhile to get it properly calibrated,but has been problem free otherwise.I did see somewhere that some of the later 323's use the S1 wheel pilot which is different from the unit on my boat. There are certainly enough of these wheel pilots around, information should be readily available to troubleshoot the system.As you suggested, there may be something else binding in the system un related to the autopilot. Keep checking for that. Look under the floorboard to see that the steering cables are properly routed and not hanging up on wiring going to the pedestal.