[Samba] How to set up a multi-subnet Samba network

[Bill Moran]

I'm looking for suggestions and pros/cons on how to implement
this.
We've got a WAN setup with 3 Samba servers, each on it's own
leg of the WAN.  The 3 sites are connected by a wireless link that
is only capable of about 200k/sec.
Currently we have 3 samba servers, each the PDC of it's own domain.
The security is distributed via NIS so that all 3 servers have the same
passwd/group info.  These are FreeBSD servers so don't yet have a 
full PAM implementation.
Things were going very well until we started migrating from Win9X
to W2K.  Problem is that folks that are logging into (for exampe)
domain X can't easily access shares on the domain server for A.
I'm guessing that this is because Samba still doesn't have support
for trusts.  With W2K, you get asked for passwords again when you
try to connect to a different server, and (believe it or not) this is just
too much work for folks.
Additionally, persistent network connections to other servers do
not work at all.
We're considering putting all the servers in the same domain and
setting up a PDC/BDC system.  The only concern is the network
traffic this will cause across the wireless links when people log in.
(Windows always tries to log into the PDC first, correct?)
So ... first off, does anyone have any comments on pros/cons of this
approach?
Does anyone have a better approach?
Does anyone know how much traffic results from a network login?

This is a somewhat open-ended question.  I'm looking for input of
all types.

TIA,

-- 
Bill Moran
Potential Technology technical services
http://www.potentialtech.com