The Mc Cann uses screw in type fixed ports.  It allows faster pulling of the gas plug and reinstall, since you just reinstall (screw in) the old fixed port plug insert.

On the other unit, you have to back out the set screw threw testing, and if you need to pull the gas plug, you have to go back to retesting to get the set screw to the needed turns out.

Note: the Mc Cann comes with 5 port sizes and if needed, you can open up one of them to get a in between size with a drill bit (pull the port before drilling).

Based on the K.I.S.S. principle, I would favor the McCann.  I'm  sure the Schuster does what it's supposed to do as well.