First of all, that is a BEAUTIFUL build!!!!!!!!!!!!!! WOW! I am saving your picture to my archive of fantastic build pics
I agree that DDC's in general are more prone to failure than D5's, although I don't know that this is the case for the MCP35X. The reason I like the 35X so much is that you don't have to reach in and manually adjust the speed, it is instantaneously done for you via PWM and the fan curve(s) you set for it. This means that, during the vast majority of use, they ARE silent pumps. The only time I've ever heard mine running was when I intentionally cranked it to full speed (or when filling the loop). Since it's only running at 30% on average, the heat issue is, well, a non-issue as well.
I am not a "fanboy", and I apologize if I came off that way. I have just gotten so used to recommending the 35X whenever another "OMG WHAT PUMP??!?!?!?!!?" thread pops up, due to its versatility and my knowing that the 35X will work pretty much regardless of the loop, that I see it as the top pick for all-around performance.
The Pump Discussion between Martin and the other (I feel bad I forget his name) Mech Engineer going on right now is quite enlightening, and I have been learning a lot that I didn't know before (I am a Biochemical engineer), perhaps the biggest of which is that the "flow rate as advertised" is meaningless; I always had a hunch, but thanks to their extremely well-written posts and pretty charts, that, as well as a number of other things, make much more sense to me now.
I recommend reading through the thread if you haven't!