Haven't tried these or even seen them for sale anywhere (store or online). It's entirely possible that they are quite good, or at least better than the junky Penn Championship that is sold everywhere based on momentum and price.
Are you sure that they are a "unique" ball though? There seems to be alot of "private labeling" going on with tennis balls. I tried some Volkl balls a while back. They were rock hard and heavy. Pretty sure they were just rebranded Dunlops!