As I promised I would like to add my review of this product as well. Sorry for the delay - Things have been crazy at work lately and I went to PAX East this weekend, so that was also crazy
A summary - I love this system! Everything is working very well for me and I have had no technical problems with it. I went with the lower-power DMA-1240 amplifier and it still has plenty of juice to drive my speakers. I am using pairs of Monoprice 4103 6.5" in-ceiling speakers everywhere except the master bath, where I have a single Monoprice 4619 6.5" dual voice-coil in-ceiling speaker. I also have a pair of JBL outdoor speakers ready for the deck but the weather has been too crappy lately to install them.
I have been using the built-in mp3 player primarily so far until I can hook up more sources. The sound quality is quite good and it is very cool to be able to see the currently playing track on the keypad. I am using an old 2GB drive about half full of songs and it has handled everything as expected with no glitches.
I have also tried plugging in iPods/iPhones to the keypads, that is a very cool feature. They are then selectable everywhere else in the system just as advertised. Sound quality here is good as well.
The keypads themselves are pretty nice looking and perform well. The rubber buttons light up when you press one and stay lit for a few seconds afterwards. You can set the display brightness separately for when the pad is in use and when it is idle. Also, you can customize the display colors! You can choose from maybe 8-10 colors for both font and background. This usefulness of this is debatable as white-on-black is certainly the most readable but it's cool nonetheless. White-on-blue and green-on-black also work well. My wife changed the master bedroom one to have purple text on a sky blue background - this of course looks terrible, but hey, anything to increase the WAF, right?

However, I do have a couple complaints. First, and most disappointingly, there is no option to shuffle songs on the built-in mp3 player! It just plays all the songs on the USB stick one after the other in alphabetical order by file name. You can tell it to repeat, but no shuffle. This annoyed me to no end while setting up and testing the system... you have to power cycle the controller if you unplug and replug any keypads, and then the mp3 player starts over from the beginning. I got quite sick of the first 5 songs on my USB stick. :P I will just write a script that will put a random number at the beginning of each mp3 file name so I can get a different shuffle order whenever I update the files, but still - shuffle is a pretty basic function these days and they should have included it.
Second complaint, the keypads DO correctly parse ID3 tags for the artist name but for some reason it tacks on ".mp3" to every song title... weird. You can see this in the picture I posted earlier.
Third and final complaint - the intercom only works when a zone is turned on. If a zone is not on you are unable to page it. You can turn on all zones from any keypad using the "Party Mode" feature, but that's not really the desired operation for me. The intercom was one of the big reasons I chose this system and this may limit its usefulness. We may end up just leaving certain zones on 24/7, however, that will mean the amplifier is also powered on 24/7, so... I dunno. A bit disappointed there.
One other thing, and this is my fault, not HTD's, but I should note it to save someone else some hassle. Be very careful when you cut out the holes for the double-gang keypads, especially if you are like me and you cut holes for them of existing single-gang holes, On 4 out of my 5 keypad locations I cut the holes just slightly too big for the old-work bracket and the face plates do not cover up very much margin. I have some drywall patching and painting in my future.

I will try to post some more pics of the installed keypads and controller hardware in the next couple days.