Yeah... since i upgraded my drobo to the 1.3.7 firmware, its become the slowest device in my system. And its connected via the firewire 800 port. My USB2 2.5" drives absolutely kill it for read write speed.
Just waiting for the thunderbolt arrays to come out, or in the case of the Promise Pegasus unit Apple have for sale, a reasonable price to be attached to it. The Drobo will then become the offsite backup unit.