While I use component video for most of my HD content, the use of the Monoprice switcher is something that I have done several times with good results.
Most HDMI gear is limited by HDCP, not by HDMI itself. So, it will depend on the device connected to it, but for the relatively low cost of the Monoprice switcher, it makes sense to just get it and try it out. Pick up a few decent HDMI cables while you are there.
SWITCHER is what you want. A switcher switches inputs between multiple devices. A splitter takes a single device and lets you show it on multiple displays. So, if you have a projector, and a plasma panel, you would SPLIT the HDMI output to both the plasma and the projector.