I always thought a low-expansion foam like urethane might fill the cracks, and stick to the dash, yet flex enough to keep from cracking again. That foam is surprisingly strong.
I'd figure the DiNoc would be difficult to wrap on the parcel shelf too, though I've never used it myself. Looks nice on some trim I've seen, IMHO a whole CF dash might be overwhelming.
I vote "go for it." I'm all for fixing an old dash. You should see how bad my e24 dash looks...