Yep.  Mining scrypt my rig pulls 1150W doing 2.1Mh/s.  On darkcoin it uses 650W doing 6.2Mh/s.

As someone else has pointed out earlier though, this reduced power consumption could simply be because there's way more code optimisation to be done yet and the GPUs are only doing 50% of what is possible.  I can make my GPUs run cooler mining scrypt coins too (and more efficiently) if I want to.

Here's another point of view...  assuming that we can't push any more performance out of the GPUs while mining darkcoin, it could be argued that it is less efficient because you need to purchase 2 cards to do the work that 1 card should be capable of, in terms of raw computing power.