Curious what you plan to do with the 2nd and 3rd Colossus cards- I thought you could only do 1 Colossus to one cable box, unless you plan to have 3 boxes stacked right near each other (or some very long runs of cable) does seem a little crazy.
If you wait another couple of months, the HD Homerun Prime should be out, and you can add one of those to the setup (with the benefit of being able to grab channel mapping data from the device).
I do have 3 HD boxes on top of one another, I record a lot of sports and all to often they overrun each other in time slots plus the rest of the family may want to record something. CableCARDs (so no HD Homerun) can't be used in my area so the Colossus are the only real option for this area. I'll be damned if I give up my telcos IPTV service for them money grabbing cable companies. The IPTV setup here is far superior then what is available for the local cable company (HD feeds are being pumped out well over twice the bitrate with the telco plus I'll be getting 200 Mbit down / 60 Mbit up internet with no data caps).