I did some more research, and summarized it here in case this helps anyone else, and also so I can refer to my notes again!
Fanless enclosures are currently widely available with USB 2.0 and/or IEEE 1394a (Firewire 400) interfaces. With a good bridge chipset implementation, both will have similar real world transfer rates, except that USB will place a higher load on the CPU than 1394a. The bulk of the market and therefore the cost effective products have these interfaces eg Bytecc, Rosewill, Vantec, etc.
There is a limited selection of more expensive IEEE 1394b (Firewire 800) enclosures. These provide a significantly higher transfer rate then either USB 2.0 or 1394a, if you have the appropriate adapter card in your PC. The Rosewill RX30-U2FAB
uses the Oxford 922 chipset and provides 1394b, 1394a, and USB 2.0 interfaces for about $100 ($85 on sale at Newegg today). The RX30-U2FAB appears to be the USA import of the Pleiades 800+
on the Rosewill page it states this enclosure only supports up to 300 Gbyte hard drives. I think this is an obsolete statement but I have not been able to verify otherwise. Note:
If you are running WinXP SP2 read this Microsoft support bulliten ”Performance of 1394 devices may decrease after you install Windows XP Service Pack 2”
to restore full 1394b transfer speed.
There are also some enclosures with a SATA I (1.5 Gb/s, SATA-150) interface, using the internal SATA type L connector. This is a stop-gap solution until the pure eSATA solutions are available (see below). SATA hot-plug requires both a hard drive that supports hot-plug and a hot-plug capable drive controller. It appears that the VIA southbridge VT8237 is not hot-plug compatible (from what I read, did not test). The Coolgear SATA or IDE COMBO SATA + Firewire + USB 2.0 enclosure (listed here
for about $60 interfaces a PATA or SATA hard drive to SATA I type L, 1394a, or USB 2.0 interfaces.
The ideal (and just emerging solution) is the eSATA interface with SATA II (rev 1.0a or later chipset). eSATA is designed for external use outside the PC case, and supports hot-plug with the newer chipsets (unless the vendor is just using eSATA physical connectors with SATA I chipsets). eSATA uses a type I connector, which is shielded and physically stronger than the internal type L connectors. The ideal solution would be an enclosure with eSATA and USB 2.0, allowing fast transfer on one PC with an installed adapter card, and connectivity on all other PCs. Products I found in this category, including some not released yet, are:
An inexpensive SATA II adapter card of unknown performance. Looks like it uses a SiS chipset: SS-108SE for $30.
The Oxford 924 DSB chipset can be used to implement enclosures with eSATA II 1.5 Gb/s, 1394b, USB 2.0 interfaces to a enclosed SATA II hard drive.
The Vantec NST-360SU connects a SATA hard drive to eSATA or USB 2.0 interfaces. Currently listed for pre-order here and here for about $45. This appears to be a USA import of the Welland ME-740J. Bytecc seems to import from this manufacturer too (by comparing case styles).
The Pleiades Super S-Combo uses the Oxford 924 DSB chipset to interface a SATA drive to eSATA, 1394b, 1394a, or USB 2.0 ports. Presumably this will turn up as a Rosewill product.
This product supports both PATA and SATA hard drives to eSATA and USB 2.0 interfaces. It supports hot-plug. Don’t know who the USA importer would be.
The G-DRIVE Q is a complete external drive (includes a drive) and uses the Oxford 924 DSB chipset to provide eSATA, 1394b, 1394a, and USB 2.0 interfaces. Prices for a 250 Mbyte unit is $289.
Based on this I now think I'm going to wait a month or so and purchase an eSATA/USB 2.0 enclosure so I can connect with eSATA and get much faster large backups.