I have an SHD on the way - should be here today - so I guess my answer has to be 'there really isn't one' depending on what you're looking for. My application is to bi-amp with a 250Hz (ish) xover between monitor tops and woofer cabinets in our living room which requires at least a couple external inputs in addition to music streaming and has to be wife-friendly.
The NAD C658 is the closest off-the-shelf competitor I think - has Dirac Live (limited version, upgradeable to the full version), and has stereo low-pass outputs potentially suitable for bi-amping. More expensive, and missing the generalized DSP functionality though. (and the low-pass outputs are almost certainly limited to a single fixed slope and probably limited to 200Hz or lower based on my experience with the D7050) . BluOS streaming which I know very little about. It does have a trigger output though - something that IMHO is a disappointing omission from the SHD.
I was weighing between the SHD and a PC-based solution using jackd/BruteFIR on a linux box. I think it should be feasible to come up with a minimalist 'appliance' style solution where you power-on straight into audio processing, but getting volume control, input switching etc would need a bit of coding at least, and probably a lot of testing. Plus, if you need to support external inputs you'd either need to use analog inputs or else SRC on the digital inputs since the jackd/BruteFIR setup will only run at a fixed sample rate. Something like the MiniDSP UDIO-8 would fit the bill, but it only supports coax inputs and of course everything I have in the living room is toslink. I eventually decided that running a homebrew remote-controlled PC in the living room was just too risky, and given that it was something of an open-ended project I wasn't sure I had the time to pull it off anyway.
So, the SHD was pretty much the only thing out there that really met my needs. Hopefully it delivers.