I have looked at these with great interest. However, a bit put off by needing the additional AC cable from the SDFB to the IEC.
It's great to know that it is possible to hard wire it in. I understand the "safety" position as a manufacturer. There are those of us that can and others that can't (or shouldn't). It would be nice to have an option of purchasing SDFB's with hard wire pigtails or terminal pads for direct installation.
One option might be to provide the SDFB's with a hard wired captive pigtail thus eliminating one AC junction.
Another option would be to build the SDFB onto the back of an IEC. (Similar to what CorCom does). I understand that this would require some technical expertise to install, just like a fully hard wired version. But would eliminate multiple contact points of a "conventional" SDFB substitution.
Some suppliers have a "DIY" section with products available for those that can.