[Samba] winbind / ldap

[Hamish]

Hello
Im not sure how to ask the question i need, but let me try:

Background:
SuSE 9.0
Samba from rpms: samba 3.0.3pre2-SuSE
Role: domain member server (winbind)

I am having a lot of trouble upgrading samba and I'm thinking of moving 
to another server. I have found that if I move the winbindd_idmap.tdb 
across, the AD / UID mappings are saved but would like to know:
a) Is this safe? (is there anything that will bomb out a few months down 
the line?)
b) can this be done with LDAP instead (I know close to nothing of LDAP, 
I have assumed it is for use as a PDC, but could it be used to store UID 
mappings as well? How 'interesting' would this be to set up?)

Thanks,
H