They work really well. I've been very impressed with the performance of the replaceable cutters on my Rebar. The problem is that some time during 2022 the replaceable cutters were updated to an inferior design. There's been some controversy over that recently because everyone started noticing the difference when the Arc was released.
There was a quality control issue with some of the batches that caused the cutters to break, and on top of that there is a small gap in the new cutters at the base of the pliers in the hard wire section which makes the cutters not work properly unless you take the time to position the wire right above the gap. The soft wire section is unaffected, however some people have noted that they have had to remove the cutters and put something underneath them as a shim or spacer in order to get proper performance.
So yeah, the replaceable cutters situation is a little fubar right now and it's not really clear if they are going to revert back to the old design. Meanwhile there is a lot of stock out there of Leatherman models that have the redesigned cutters, so if you buy a new Leatherman right now then you'll probably get the bad cutters and you might even get one of the bad batches that break easily.