Help making sense of firewire disk enclosure dilema

I have a machine running 5.2.1-RELEASE-p6.

I purchased a pair of "Vantec" USB2.0/Firewire enclosures (NST-350UF)
for some 80-ish GB IBM Deskstar drives.

The first enclosure worked great (once I got past the kernel panic
because it didn't like something that was hanging out in the partition
table area).

The second enclosure was problematic.  If I attached via USB1 (all I
have), it worked fine.  If I hook it up to a G4 Powermac running OSX
Jaguar (current-1?), it works fine.  But when I connect it via
firewire to Servant, GEOM never recognizes/creates a daX device.

I talked the seller into exchanging it for me (and hid a little magic
marker dot inside just in case), and just received the replacement.

It's behaving the same way.

Here's the relevant section of /var/log/messages for the one that
doesn't work:

   Aug 21 17:03:11 servant kernel: fwohci0: BUS reset
   Aug 21 17:03:11 servant kernel: fwohci0: node_id=0x8800ffc0, gen=3, non CYCLEMASTER mode
   Aug 21 17:03:11 servant kernel: firewire0: 2 nodes, maxhop <= 1, cable IRM = 0 (me)
   Aug 21 17:03:11 servant kernel: firewire0: root node is not cycle master capable
   Aug 21 17:03:11 servant kernel: firewire0: bus manager 0 (me)
   Aug 21 17:03:11 servant kernel: fwohci0: txd err=1b ack tardy
   Aug 21 17:03:11 servant kernel: node1: resp=35 addr=0x400
   Aug 21 17:03:11 servant kernel: probe failed for 1 node
   Aug 21 17:03:17 servant kernel: fwohci0: BUS reset
   Aug 21 17:03:17 servant kernel: fwohci0: node_id=0xc800ffc1, gen=4, CYCLEMASTER mode
   Aug 21 17:03:17 servant kernel: firewire0: 2 nodes, maxhop <= 1, cable IRM = 1 (me)
   Aug 21 17:03:17 servant kernel: firewire0: bus manager 1 (me)
   Aug 21 17:03:17 servant kernel: firewire0: New S400 device ID:0050770e00011205

I then pulled that drive out, and put it in the enclosure that works,
and it appeared as da2.  Here's it's info:

   Aug 21 17:11:13 servant kernel: fwohci0: BUS reset
   Aug 21 17:11:13 servant kernel: fwohci0: node_id=0x8800ffc0, gen=7, non CYCLEMASTER mode
   Aug 21 17:11:13 servant kernel: firewire0: 2 nodes, maxhop <= 1, cable IRM = 0 (me)
   Aug 21 17:11:13 servant kernel: firewire0: root node is not cycle master capable
   Aug 21 17:11:13 servant kernel: firewire0: bus manager 0 (me)
   Aug 21 17:11:13 servant kernel: fwohci0: txd err=1b ack tardy
   Aug 21 17:11:13 servant kernel: node1: resp=35 addr=0x400
   Aug 21 17:11:13 servant kernel: probe failed for 1 node
   Aug 21 17:11:17 servant kernel: fwohci0: BUS reset
   Aug 21 17:11:17 servant kernel: fwohci0: node_id=0xc800ffc1, gen=8, CYCLEMASTER mode
   Aug 21 17:11:17 servant kernel: firewire0: 2 nodes, maxhop <= 1, cable IRM = 1 (me)
   Aug 21 17:11:17 servant kernel: firewire0: bus manager 1 (me)
   Aug 21 17:11:18 servant kernel: firewire0: New S400 device ID:0050770e00002251
   Aug 21 17:11:19 servant kernel: GEOM: create disk da2 dp=0xc4924050
   Aug 21 17:11:19 servant kernel: da2 at sbp0 bus 0 target 1 lun 0
   Aug 21 17:11:19 servant kernel: da2: <Prolific (1394 ATAPI,Rev 0102> Fixed Simplified Direct Access SCSI-4 device
   Aug 21 17:11:19 servant kernel: da2: 50.000MB/s transfers
   Aug 21 17:11:19 servant kernel: da2: 73308MB (150136560 512 byte sectors: 255H 63S/T 9345C)


Am I doing something wrong, or should I just stop buying cheap
problematic junk enclosures?

g.