I recently bought a CMM 58" gear-drive after considerable research including the Caroni. It looked pretty good, and I have no doubt that it is a quality tiller that will perform well, but I concluded that gear drive was probably better.
When you look at the lines offered by most manufacturers, you see that for those manufacturers that offer both gear and chain drives (Woods, Bush Hog), it is when you move up to their top of the line commercial and heavy duty models that they switch from chain to gear drive. That suggests pretty strongly what the better system is.
I have not used mine yet, because the ground is still too soggy here in Massachusetts, but I hope to w/in the next couple of weeks and will post further on it then. I am impressed, though with the weight, fit and finish and apparrent quality of construction of the CMM. The photos on CMM's website just don't do it justice in this respect, it is one SOLID attachment and looks like it is built to perform and to last. At a price that equals or betters the "bargain" class of chain-drive tillers I couldn't find a better buy and Mark at CMM was a pleasure to deal with from start to finish.