The receiver of your dreams does exist and it's called a PC.
Get a satellite tuner like the Prof 7500 and a HDHomeRun for OTA and you're golden. Plus since your PC is the receiver you can record directly to a share right from it.
All this would cost less than a dedicated box and perform better.
Well, maybe. I already have a small HTPC but it runs Linux and as far as I can tell, the Prof 7500 requires Windows (seriously, I am not going to buy a Windows computer just so I can run a satellite tuner). Also, when you start getting into this type of setup, it tends to require computer skills that I don't really have. Even getting the HTPC box working was a major undertaking and it's mostly standard stuff (Ubuntu Linux + XBMC, still there were several pitfalls that took hours to resolve). To me, the attractiveness of having the type of receiver I envisioned would be that it would be "plug 'n' play", without requiring me to be a genius at computers. I can handle plugging in a network cable, but not things like trying to resolve unmet dependencies, etc.
I an guessing that there are other plug-in satellite tuners similar to the Prof 7500; I wonder if there is a comparison chart or comparative review anywhere?
One receiver that I've not seen reviewed on this site (if it is then I missed it) is the Amiko Alien that Jim S. mentioned, of which there appears to be more than one model. Again, I wish I could find a good comparative review of that somewhere; it might do what I want but I honestly can't tell for sure from what I've read.
Anyway, thanks to those who have responded; I may just keep using my Diamond for another year or two and see if anything closer to my "dream machine" come along.
In the back of my mind, I keep wondering, if the MicroHD is based on Linux, could it be made to network with other computers (and maybe share video) if it had a
USB to Lan RJ45 Network Card Adapter attached? I guess I should ask that in one of the MicroHD related threads. I'm just really surprised they didn't include that capability from the beginning. The problem for me is that even if it could be made to work, I do not have the skills to do it, unless it could be made to work automatically in the firmware (whenever an adapter of that type is connected to the USB port).
Thank you again to everyone who has responded so far. I am taking everything into consideration but so far nothing has impressed me as something I could make work the way I want it to.
NOTE: The eBay link above is just the first item I found on eBay that looked like it might work for the purpose. I am
not saying that it is either the best or the least expensive device for this purpose, and I am definitely not saying it would work with a MicroHD out of the box — I simply have no way of knowing.
EDIT: Replaced original link with 10/100/1000 device per guacharaca's suggestion below.