I use two InXtron (was MacPower) SK-3500 Super-S (contains a Oxford Semiconductor OXUF934DSB bridge) with two WD WD20EARS and a 3 m FW800 9-pin cable (good quality, very good shielding). The enclosures support FW800 and daisy chaining. The read/write speed in this configuration: up to 95 MByte/s. This configuration is very silent.
Btw, you should probably buy the SK-3500 Super-S3, because it supports USB 3.0 (supported by Ivy Bridge CPUs) and has newer firmware, which supports drives > 2.2 TB.
Personally, I use a DroboFS, but I also live in two worlds (windows and Mac) all day. So for me I need a very open storage solution that works well and reliably. The Droo is not the fastest solution on the market today but then again I'll take the performance hit over a good backup solution.