So by bridging the gap on that old piece you are taking away the ability to adjust the tension on the z axis rails. If that was causing you chattering you should have been able to tighten the long bolts to help that out.
The new , currently recommended, part actually ties the 2 half of the middle assembly together in 3 places instead of just the one. The increased rigidity significantly when we started using it, it also allowed for much larger tools as they didn’t sag.
You should try the new part, you need 2 of them instead of 4.