I doubt you'll see a counterbalanced option anytime soon at retail. It's been tried and I think the market has spoken on its (lack of) desire for counterbalanced putters.
This is something that would be extremely easy to build yourself. Put a shaft extension in a Mini to get the length you want, and then get a SuperStroke grip with a counter core. Done. Or you could get counterbalance with another grip by going with a Tour Lock counterbalance system and have more options for how much weight you want. If you need weight in the head, put lead tape on the sole until you get to the weight that feels right. If desired, you could replace the lead tape with an appropriately sized sole weight later.
DJ uses a counter core grip, but it's my understanding that he doesn't always have an insert in there.
My point about lead tape was it could be used as a short term option to figure out what weight you want in the head before you buy a weight kit. But if you don't mind buying different size weights and seeing what you like, but all means do that instead of lead tape.
Well, this might be one of those clubs that does not fit for everyone, I might be lucky enough to be in the general targeted audience. Although it may not be the greatest club, but it's not too bad either