Rollo,
Sigh.... I hope the Nvidia paychecks are good because you're doing a great job of guerrilla marketing. If not, I'd negotiate.
I looked into this (as simply an EE with absolutely no connection to ATI) and began speculating what ATI is doing. Now, I'm not the actual designer but I can still use some logical deduction.
First, the truths I'm basing my premise on:
1.) The only card that needs to be special is the master video card (a "crossfire edition")
2.) The signal from the slave card is delivered to the master.
3.) The final picture is created in the master and output to the display.
These are all things I'm 99% sure are correct.
Now for some speculation:
The slave is likely creating half the image (resolution reduced or actually just half the screen) and is then transmitting it to the master. This is then buffered and combined with the picture created by the crossfire edition card. The final output will be an image using both the output recieved from the slave and the master but from the master.
I'm no expert but, you know what, this is the logical way to do something like crossfire/sli (at least elegantly

).
Anyway, what's my point. Well, if you want to recieve a signal that is not the full resolution, why would you use a reciever other than one that meets your specs. The SiI 1161 will work great as a reciever of any halved/reduced-resolution signal the slave can throw out. The SiI 1171 would be overkill.
So to conclude, ATI has not dropped the ball. Just because some schmuck at rage3d writes something doesn't mean you should assume he knows what he's talking about.