Many HDMI sources, one TV and one projector

I used to have a very similar setup and the key was the HDMI lowest common denominator principle. HDMI only sends out a single video stream and a single audio stream at any time. So those audio and video signals must be compatible with everything connected. So the signal gets lowered to the highest quality signal that all sink devices (your displays, for instance) can accept. So if your TV or project can only *accept* 1080i, then both sets will be limited to 1080i.

Now, notice I said "accept" and not "display". Many later model 1080i displays accepted 1080p inputs. So, in that case you would be able to send 1080p to all devices.

Remember this lowest common denominator applies to other HDMI video formats, such as 3D and HDMI audio. The audio is probably not important here since you are using S/PDIF. Hopefully for Blu-Ray you are using the 5.1-channel analog inputs since those are a significant improvement over S/PDIF for Blu-Ray discs.

The other thing you would need with a matrix switcher is a universal remote so that you can change your matrix switchers at the same time you change your receiver inputs.

In case of most splitters you have right. The HDMI signal must be compatible with everything connected. But there are also some splitters, which allows that signal does not have to be compatible with all connected devices, but only with all switched on devices. An example of such splitter is nSplitter QS at iHDMI.eu It allows to connect 2D and 3D displays to its HDMI outputs without loosing the possibility to watch in 3D (when 2D display is in stand-by). The same with the 1080p24-capable displays mixed with devices which do not support this format.

The "danger" with this type of splitter is that the EDID can change while the source is sending. There are some sources that cannot handle that type of change in the middle and will hang (or otherwise have issues). For some it will work perfectly, though depending upon the sources used. It solves some problems and introduces others...

For me the nSplitter QuickSwitch mode works perfectly. I have new 3D plasma and older 2D projector which does not support the 1080p24 format. Usually I have only one of the displays switched on and then I can always watch the best of supported formats on it : 3D 1080p in case of plasma, and 2D 1080i in case of the projector. Sometimes I use both and then 2D 1080i is displayed on both screens like always in case of any regular HDMI splitter.

When I'm switching on/off any of displays during watching the video on the second one (which is very, very rarely), I have few seconds of the black screen, that's all.

Your can check yourself how your equipment reacts to the EDID changes by unplugging and plugging again the HDMI cable during playback. Remember to have the CEC autoswitching_off function deactivated.