I have gone to half a cake or better yet harvesting into a graduated 2 liter Ehrlenmeyer flask and measuring out the pitch using Mr. Malty (and adjusting for thickness encountered). I have really liked those results.
I did this recently except using a sanitized measuring cup. I took into consideration the amount of dead yeast and trub mixed in with remaining live yeast of the yeast cake after the first ferment. So where Mr. Malty Yeast Calculator recommended 7 oz. of yeast slurry (I assumed Jamil means from a recently completed starter), I took ~12 oz. from the bottom of the bucket, and added all of that into the second batch in a clean bucket.
I monitored and per the same cool pitch / gradual ramp temp-controlled process that I had used on the previous batch of the same SG, it took a similar time (3 days) for a healthy krauesen to visibly form on the surface of the second batch.
So my assumption was that this equated to a fairly equivalent "appropriate pitch" since I calculated the first batch also per Mr. Malty, but for rehydrated dry yeast.
I DO appreciate the different responses identifying that either way (whole or partial yeast cake) generally provides high quality results. I'm taking that into consideration for future opportunities!