I just bought the UD-5 (last week) and I must say I'm very pleased with it, although I must admit I do go through SATA ports like nobody else. By the time you have a couple of RAID0 arrays in there plus a couple of other eSATA devices (a DVD and a Blu-ray writer/player), then a couple more eSATA external drives, you are starting to need all those ports. However I'm a photographer and really need all those disks and esata external backup drives, maybe if you are just into gaming and a bit of office work, then the number of ports available is overkill.
Also I immediately went to 12Gb RAM, you can never have enough of that working with the 64-bit version of Photoshop.