The Halcyon Infinity including the Cinch is allowed for Fundies, and I used mine for Fundies.
Having said that, while the Infinity meets the requirements, we get back to the concept of bringing more than you need.
If you take Fundies, the GUE instructor may give you compelling reasons to remove some of the extra components. I let him remove everything from my Infinity except the back pad and the Cinch. I was using weight pockets on the cam bands since the weight pockets in the Infinity weren't in the right place for me, so I let him take them off. He showed me that every time I tightened or loosened the Cinch, the bp/w might raise or lower differently, and I don't have a long torso. So I accepted his offer to disable my cinch with tri-glides. I removed the cinch a year later, so it became stripped down to a Halcyon Eclipse with a back pad.
I never thought I would part with the "extra" components of the Infinity, but like many divers, they sit stored away and I don't need them one bit.