I took a really close look at the fit, to see if I had missed something. Because for me, the boot is rock solid in the binding, and I like the C60 (although, I am tired of an uncomfortable binding. I heard the 06/07 models are more comfy). I found two compatibility issues, and just hinted at one of them.
1. The Malamute liner is pretty thin, no padding, no bulk. It gives me a good tight fit that stays firm. That gives the boot a lower volume and offers less cushioning on the rear of the calf muscle. The C60 highback is stiff carbon and it ends pretty bluntly, with no rubber flange (rude word) protruding from the top of the high back. This creates a pretty harsh edge running across my calf muscle below the top of the boot. This edge causes discomfort that I would rather not have.
2. The front of the base plate is wider by about 10mm than the wide point of my boot toe area. Once strapped in, this does not cause any movement at all, its solid. But as I tighten the toe cap-strap it pulls my boot toe across the base plate, whist my heel stays in place. So if I set my rear binding at +7, I end up with a foot angle (not binding angle) which is only +1, perhaps zero. If I had a rear angle of -5, then after tightening the toe strap I would have perhaps -10 or more. Get the idea? So all this time in C60's I thought I was riding +7 on the rear whilst in fact my foot was positioned in the binding at a much lower angle.
So perhaps there is some truth in the claim that Malamutes and C60's are not compatible?
I have 05/06 Mutes and 05/06 C60's. The ride performance is good so the worst case is that non-compatibility causes calf discomfort more than any performance issues (although that discomfort has led to me being less comfortable performing over a hard day). Just watch what angle you are really running. It may well be a bit different to your binding angle.
I reckon I will hang out for the Spark Research Wonder Binding and then alternate between them and my hard boot rig on the split.