In our latest video we talk about our experience with the Metabones CINE Smart Adapter, which iterates over the T Smart adapter with a locking ring.
We found that the adapter was useful when used in situations without rails and lens support, providing a nice solid lock and eliminating some adapter shake when focusing. But we think it can lead to difficult situations if not used with an assistant or a firm tripod, as the locking ring can be super difficult to use. But if you had lens support on rails, you don't really need the CINE Smart Adapter.
We'd like to see a locking adapter that worked like RED's locking EF. First creating a positive connection, then lock, instead of doing both in one step. But for now, this will be very useful for slim camera builds working with one variable zoom in documentary and wedding scenarios.