FD, we are just finishing our first B&K install here is what I have;

2 CT600.3s
1 K4 (Kitchen)
1 T2C (media room only)
1 T1 (Master Bedroom)
1 RP6 w/ 2 RM433s
1 CB4

I also have 9 inputs (3 sats & 6 cameras (she wanted each camera on a different input and no DVR)) plus the 6 tuners.

I am using all IR, no RS232. I downloaded the codes from B&Ks website and everything works when I changed the settings in RTI (had to take off the repeats and sustains). I am able to control all zones from the K4. Plus with IR the macros pretty much build themselves. We finished yesterday, but the K4 has been working for a week. Only issue is that their cheap JVC LCD TV won't respond to any IR codes, even those learned from its own remote.