I am early enough in the design process to choose the best steering for the bike (APS with HCS).
In looking at hard linkage, bump steer is a big issue to overcome. Cable controls solve the bump steer issues, but bring in a whole new set of potential problems that have to be addressed. As in all engineering designs there are always tradeoffs that have to be considered. I have designed and machine the axles and hubs ( out for anodize now ), how to set up the steering controls is still not settled.
There are some European bikes with HCS set up to road race using cable controls, if you read their reviews, steering control doesn't seem to be a problem with cables.
One thing is for sure at this point, the total investment to build this bike is going to be way to much, so not passing tech or having handling problems is "NOT an Option".
Rouse