I have the P5Q board. There's the intel ICH10 controller (6 ports), and a Marvell 6121 controller (2 ports). eSATA works better with the Intel chip, which needs to be in AHCI mode, not IDE. Hotswap works correctly for me.
Turn on Drive Xpert in bios setup to use the sata ports on the Marvell chip (Normal Mode) - this is unstable with the latest drivers, I found hotswap works sometimes. The 12069 drivers worked best for me, they tend to delay the system boot. My opinion : the 6121 is troublesome, don't bother.
Yes there's little detail in the ASUS manual on this topic, I had to work this out. Good thing I have ESP.
The Marvell does provide a useful PATA interface.