I have had an Octava 4x4 HDMI Cat5 matrix for several months now (got it right when they first offered it back in September I believe).
My setup is as follows:
Inputs 1 & 2: DirecTV HD DVRs
Input 3: Popcorn Hour C200
Output 1: Yamaha receiver feeding 5.1 surround speaker setup and Panny P54V10 plasma
Output 2: Pioneer-PDP 4270 plasma (TV speakers only)
Will be adding TVs sometime in the future, so the additional outputs are there when I get to them and I still have space for one more D* box if need be.
Okay, that's the setup... how does it work?
In a word, GREAT.
Basically, it's been plug and play since the get-go. I have 2 CAT6 running to each of the TV locations for video use (plus a couple of other CAT runs for network and IR use). All of the source equipment is consolidated in the basement. Since I'm using CAT6 runs from this consolidated space, I did need to purchase an extra Transmitter unit from Octava so that I could keep the receiver in the basement. My runs end up as follows:
Switch Output 1 >HDMI Cable>AVR>TX Balun>CAT6>RX Balun>HDMI Cable>TV
Switch Output 2 >CAT6>RX Balun>HDMI Cable>TV
The CAT6 runs are about 50' and 80-100' in length and I've had no picture issues whatsoever. Changing sources is practically instantaneous (less than a second) and unlike the Monoprice switch this replaced, changing sources does not cause ALL displays to go blank. With audio - again no real issues. I have a 5.1 system in the family room and just the regular TV audio out in the bedroom. No issues playing any source in either place or the same source in both at once.
You can set each output to use EITHER (not both unfortunately) the HDMI output or the CAT5/6 outputs simply by holding the output switch on the front down for a few seconds - it toggles between CAT/HDMI mode. In addition, there is a set of dipswitches to control EDID functionality, but since I haven't had to do anything with them, I can't really comment on how well they work.
The matrix includes IR passthrough functionality, but I can't really comment on it as I haven't been using it. Since each piece of my equipment has distinct IR codes, I've got a simple Xantech IR distribution system with a connecting block pulling in remote IR from around the house via Dinky Links and transmitting those signals on to the sources.
Speaking of IR though - the IR control is pretty bog standard... although a LOT better than the Monoprice units (they seem to have rather weak IR sensors). I set up everything to use my Harmony One and it works great. One thing to note if using the Harmony software; IIRC, it did find the switch in its database, but the codes it used for the sources didn't work for me. So I manually taught each command into the Harmony (all 8 or 9 of them!) and had each activity perform the desired two-command operation as appropriate (e.g. Display 2, Source 1 etc.) No additional changes for interkey delays etc. were required and the remote works great in activity mode. In Device mode, the Harmony can be a bit picky making sure you click the Display button and then the Source button in a short enough time, but it's rare that I have to do that so I'm not too concerned. Eventually, I'll move everything to RS232 control and it's good to know that Octava have this covered too, including an RS232 port on the unit.
Octava are VERY helpful indeed and I've had several e-mail conversations with them discussing the best ways to set up the equipment I have and also just talking about HDMI issues etc. in general. Definitely a company that likes to look after their customers.
Bottom line is that for a mid-range switch and relatively new equipment, this has worked great for me. I haven't tried hooking up the Blu-ray player yet and probably won't since I use the Popcorn Hour for movies etc., so you might want to check with Octava themselves to see if they have any recommendations along those lines (I hear some BD players are quite painful to integrate into HDMI matrix setups). All in all, I'd recommend this setup to anyone interested. If you don't need the CAT5/6 functionality, they also offer a cheaper (~$499) 4x4 HDMI only matrix which I would presume handles the switching duties as well as this one.
UPDATE: Although my overall opinion hasn't changed with the switch, I have come across one area of concern. If I'm watching a source with 5.1 audio (or better), I can't view that source on my Pioneer TV (or more specifically, I can view it, but can't hear anything!) I hadn't noticed that before since the D* boxes are set to output non-Dolby Digital and we watch the PCH content (i.e. movies) on the 5.1 surround system anyway. *IF* you have a TV that can decode 5.1 then this is a non-issue. If your TV can't decode 5.1 then you may run into issues. This is more an issue with HDMI than the switch, but there is a (albeit somewhat costly) solution. You can either run each HDMI output via a receiver that can decode 5.1 or you can use the combination of Octava's 1x1 HMDI Audio/Video splitter (~$160) and Gefen's DD decoder (~$130). That will allow you to split off the audio, decode the 5.1 signal and then provide an output for your TV's audio input. It's not perfect, but it works. Like I said though, if you have a TV which can handle Dolby Digital audio input (and a LOT of recent TVs do apparently), this isn't an issue.