It's true that some presser feet have a spring on them and others don't. When you talk about "hopping," there's some hop that comes from the machine. If you put your presser foot on and watch it as you turn the handwheel, you can see the hop. It's a built-in eccentric on most machines.
I'm sure having fun with the Westalee ruler foot and templates on my Bernina 230. I've ordered the Bernina #72 ruler foot for the store, but they said they are "way back ordered."
The Bernina #72, #9, #24 and #29 feet all have the spring on them and the Westalee ruler foot doesn't.