ORIGINAL: da Rock
Only reason to not use something is if it sticks or flexes. A braided cable inside a tube is good if each end of the tube is locked down, and the cable is not binding in the tube. Use that setup almost every airplane. Now that the carburetor arms are plastic, nothing to avoid up there.
There is so little force required to control a carburetor, there isn't really any setup that doesn't work if it's installed correctly.
That's pretty much how I feel as well, but I made the change on my trainer to a hard rod and it seems to work pretty well, I think there was a bit of flex in the cable and it was starting to fray so it was time to change it anyway. I also put a rod into my GP .40 Cub, but it was more of a necessity for that, I had to put a couple of bends in the rod to get it in the right spot, if I used a cable it would not have worked as well, it also looks pretty cool!