Yesterday I brewed 10 gallons of Skotrat's Traquir House Ale recipe. This morning I have 3-4 inches of krausen in each of my two glass carboys. Fresh microbrewery Scottish ale yeast slurry is a wonderful thing.
I have done what you describe a couple of times, with one tweak. After I siphon the beer off the yeast, I dump in a can of factory beer like PBR or Coors so that the yeast remains covered with beer. Then I try to siphon off the factory beer as much as I can (tilting the fermentor) before adding the fresh wort to the yeast cake.
I don't know if its necessary, but I just don't like the idea of the yeast cake being exposed to air.
I am storing some kegs of mead for a friend who took a job out of state, and had to move. Some of them are over 10 years old.
One day I had my pressure gauge out and thought I would check the pressure on the kegs. One of them was 40 psi! I burped it back down to 10 psi over a few days, and pulled a sample. Delicious! It apparently just kept fermenting in the keg.