Got my Harmony 900 a few days ago. After a few goofs (on my part) I finally have it set up to run my whole HT plus a Lutron light dimmer.
I had a bit of frustration setting up an activity to run PS3 using the Nyko adapter until it dawned on me that I hadn't set the device to run in rf mode (slaps head).
It turns out I don't need to use the mini blasters after all. I have my tv on the north wall of the media room and my a/v cabinets on the west wall. What I tried, and found actually worked, was to situate the blaster on a book case shelf on the east wall. The amazingly wide angle of the blaster controls all the a/v devices and the tv. The a/v devices are behind doors, but the doors either have semi-transparent glass or steel mesh, and the ir signals pass through reliably.
For anyone thinking about getting a Harmony 900, I give it two thumbs up.