As you know on the EF with its coilpack setup you can't adjust timing. My question is, what bearing does that have on cam selection and performance?

Hi There

Generally, you can still choose the cam best suited to your
needs / expectations but also install a vernier cam gear.

Some cams will perform fine in the factory default position,
but others may need a tweak or two.

As long as the cam isn't too wild and needs aftermarket ECU assistance,
then a vernier gear can help to optimise the performance
of the cam by allowing you to advance or retard the cam timing.