Works for me and all my Elk products, however it did not work for me with my Honeywell CIA modem, and vice versa, my Keyspan USB would not work with the Elk panel I tried it with.
Same is common for many manufacturers, they typically find a manufacturer whose product/drivers tend to play nice with their hardware and recommend/support that product, otherwise I would not have 4 or 5 USB to serial adapters sitting in my laptop bag for the hardware I install/support.