I have 2 Lexar 16GB x400 and two x1000. SDHC cards I have 2 Lexar 16GB x600 and two x600. Thom Hogan recommends using 16GB over 32 GB to help negate loss of images if the card fails.
I use the x1000 CF and x600 SDHC for wildlife where speed of buffering is more important and the X400 CF for landscapes/portraits where buffering speed is of no concern. The SDHC cards are purely for either RAW or jpeg backup.