someone writes:

I have noticed that the connex links have to be installed in the
correct orientation or they do cause some skipping. Predominantly
on the smaller cogs, 11t-13t's.. Larger ones didn't seem to affect
it. I mistakenly did one wrong on my own bike and it was painfully
obvious in the stand that it just didn't fly, so I flipped it, and
life was good.

There is another problem with them, but it is mostly on the Shimano
ones.. They seem to have a propensity to break.. a run of chains
with weakened/weak side plates got made, and the link pins pull
through. Not cool. Warranty them out though.

This is a far more serious matter than cost. It's safety. When a
chain beaks in a standing sprint the rider generally flies over the
bars. This is why you shouldn't sprint in top gear on SA-AW
three-speed hubs. They reliably pop into neutral under load and speed
due to a basic design problem for which they should be taken to court
for damages. A known chain link flaw such as what you mention is
likewise a major hazard.

Jobst Brandt