Flakey gvinum

Is anyone using gvinum under 5.3 for mirroring? I had vinum working 
fine under 5.2.1 but now I've done a clean install with 5.3 and I can't 
for the life of me get gvinum to work properly.

I've got the following setup which seems to work:

drive root_disc_o device /dev/ad0s1b
volume root
plex org concat
sd drive root_disc_0 length 0

I have similar for both swap and /usr.

When I add a mirror for / and swap all seems to work fine. When I try 
to so the same for /usr, it defines it OK but when I start it I get 
thousands of messages on the console. Unfortunately it's all too fast 
for me to see what they say and they don't seem to be in 
/var/log/messages.

My system is now a bit stuck. I've managed to zero the second disc so 
there are no drives defined for it but gvinum still knows about the 
plexes and sd's. I can seem to rm the plexes but when I try to rm the 
sd my machine panics.

I've had no end of trouble installing this using gvinum. Is it really 
that fragile as I seem to be able to crash it quite easily. I'm ready 
to give up with mirroring as it's giving me just too much trouble.