Eric,
I don't know how "great" my advice is but the Zipper wand is pretty amazing, its performance speaks for itself. It is a high quality precision made wand ideally suited for cleaning/restoring commercial carpets. I understand enough about manufacturing to know that you are constantly having to change, modify, add additional features to an existing product to attract new customers or different markets to keep the doors open.
I think your T handle is a feature that will save a lot of cleaners from themselves. But who am I to say what tool a cleaner can or should use. I hate to see you water down your design and compromising the effectiveness of the Zipper. If you are able to decrease weight, maintain cleaning performance AND give cleaners an option of wand handles for residential cleaners than that's a win-win-win and my issue of keeping the T handle to save cleaners shoulders is immaterial.
Continued success to you,
Bill