I'm not familiar with the CM15A situation... are they trying to "emulate" a CM15A with the CM19A/TM751 combination, perhaps?
Sort of. They are out of stock of the CM15A (and have been for a while now).
They decided to put a CM19A and a TM751 in a box, and slap a "CM15K" label on it, selling it in place of the CM15A.
They are strongly indicating that it is an equal substitute for the CM15A, but it is severely lacking:
1. It has no internal memory, so it needs to be connected to a running PC 24/7.
2. It has no PLC transmitter, so they give you a TM751, which is "impolite," and can cause PLC collisions.
3. It has no PLC receiver. They have no solution for that one. The setup is "dumb" when it comes to PLC triggers (like from the floodlight motion sensor, or a PowerFlash module, or a plug-in controller).