Sorry for the late reply.
JAP (Just Add Power) is indeed a HD HDMI over IP solution. I like it. No stock in the company ;-). It is just very scalable, and simply always works. It allows all kinds of HDMI signals with 5.1 sound from any source to go to any TV in any configuration. So if you have say a cable box and an HTPC, you can transmit those HDMI signals into your switch, and then the HTPC output can go to tv 1, 3 and 4, while you watch cable on 2 and 5. Clearly, the advantage of this system increases with more sources and more screens.
Control4 is a very nice home automation system, mostly because of the very smartly designed interface and the phenomenal software that integrates various pieces of hardware seamlessly. I use Control4 in a very limited fashion at the moment. I use a single controller unit. The software allows for very easy control of all my equipment, including cable boxes, apple tv etc. Most importantly, I can control the JAP switch with a the same phenomenal software, even with my ipad or iphone.
Control4 divides the house up in rooms, and determines per room what the audio and video endpoints are in that area. In normal terms, it basically asks you what speakers and TV you use. It controls the volume and "channel" choice for you. "channel" in quotation marks as it can be anything, including streaming media from a home server using the control4 hard and software. Technically, I actualy only use one "channel" which is the just add power channel and I switch channels not at the control4 level, but at the JAP Switch level.
I have an extensive HTPC with JRiver as its core software. Basically, I started out with this machine and wanted to use it for all of the above. Technically, I was able to get multiple screens set up and the audio zones worked really well. However the video component is simply not good enough for day to day multi user use. I did look into cable cards and configurations with multiple graphic cards and even multiple cheap "thin client" slave units with individual graphic cards. I can make it work with streaming of video and such, but it did never reach the quality I was looking for. Having said that, the reason to do it this way was to save costs and by the time I had a working configuration, the costs had actually ramped up as well, but without the quality or easy of control I was looking for in my rather large setup. So no dig at JRiver, at all, it is the best of the crop. One thing i maintained from these days of trial and error is the audio distribution. This is outside of control4 (largely) and done by running separate individual stereo cables to my audio zones. I have a couple of amps in my AV rack and that supplies the power for the music. This is still in evolution. As described earlier, JRiver/HTPC does not integrate well with Control4, but for now this is the solution I chose from a cost/effectiveness perspective. Using a multizone (and you quickly will need 5 or 6 zones) amplifier that has a control4 driver is ultimately the way to go and my way to go, as soon as I have the time, energy and cash to buy that.
I use my HTPC for so much more nowadays. I use JRiver on the HTPC to play all my server stored music and video. I use the theater view interface for this and it is beautiful. I browse youtube with it and access netflix through it. If someone else in the house is watching the HTPC channel, i can still get to my movies on the server via my PS3 or even using the DLNA client on some of my TV's. I also use my HTPC as the main computer in the house. Keyboards in every room, mouse in every room and you have a super fast (gaming) PC in every room of the house! browse the web, do what ever. I love it. Not easy to do, but if you have dropped enough Cat6 (you need 2 per room at least), you have plenty of cable to run a USB extension into each room as well. Logitech keyboards/mice will then be your wireless keyboard and mouse of choice. But, mind you, in this set up the HTPC is only one option on my TV's and I can also control the HTPC using the JRemote app or webgizmo and run it even without using the TV's or keyboards and stream it to any other laptop, padtop or phone in the house. It is a truly versatile system. It would be perfect with an IP controller of JRiver build into a Control4 driver, as I could then control JRiver volume directly using control4 software. now I control the volume of the htpc per zone by using JRemote. It is soo close, i can taste it. Unfortunately, i will likely soon have to spend a bunch on a mulitchannel amp/matrix because of familial complaints. I will still use JRiver as my main gate way into the HTPC because it is just fantastic software for this purpose.
I think JRiver is fantastic software. The setup I describe above is beyond what i ever expect from JRiver. I use JRiver for my media room for instance. Fantastic.
Couple of quick notes:
live radio is easy using control4 and a good receiver. Onkyo comes to mind. If you want to feed it to all zones, you may truly need a control4 audio matrix/amp for room level control of volume and input.
Control4 people only do control4. The system described above is well above the average Control4 dealer. You will have to drive that boat. They can help you with your home automation though. Or find someone who knows enough about network computing to set it all up for you.
Next, drop enough cables! In 10 years from now, you will be looking at something completely different and wireless, I am sure. For now, wired solutions are still the bomb.
Lastly: this is a hobby like no other. warn your family. This is not an out of the box solution ;-)