They use the same chipset but completely different hardware and design, it's designed in-house by HD Digitech themself.
Only common parts PCH and HDX have is the Syabase middleware and Sigma 8635 chipset.
As you know the chipset is not alone responsible for how the quality of signal will be in the end, the 6 layer PCB is one important factor here.
It's based on Syabas middleware so they use the same firmware.
PCH doesn't have SATA
PCH doesn't have RGBHV output.
PCH doesn't have S/PDIF Optical Toslink output.
PCH doesn't have 2 USB host ports, PCH got none!
PCH doesn't have 256MB Flash, only 32MB
PCH doesn't have a high quality aluminium case.
PCH use low quality components on the component board, PCH doesn't have a 6-layer PCB.
HDX-900 is a high quality product, if you don't want that and...
Check out HDX 900 at http://www.hdx1080.com/index.php?opt...d=20&Itemid=97
I just ordered one and Secrets of Hometheater Hifi and High Fidelity gave it great reviews.
I have my plasma centered at the same level as my eyes, that is the correct height you should install any screen, not above or not below.
Just sit down in your favourite recliner and then meaure the height from the floor up to your eyes.
Then install your plasma where the center of the screen is at the same height as your eyes.