DSL Warehouse DSL906E as a bridge

We're moving from an antique leased line to one of Demon's business
ADSL things (the 1Mb/sec one). We're going to be using the non-NAT
thing (with a /28 network at our end which is the same as we already
have). We have an ethernet router which does firewalling and so on -
and more importantly that I understand - which I want to continue to
use.

As far as I can see this means that we want to use the ADSL
router/modem as a bridge so it just acts as if it's not really there
at all, and the WAN side of our existing router `sees' out directly.
In particular we don't want firewalling or other stuff to happen in
the ADSL router.

Asking Demon about this results in `we don't support that but it might
work' which is not very useful - surely anyone with a non-trivial
internal network is going to want to do something like this...

Having searched in this group and elsewhere, it *looks* like the DSL
Warehouse DSLW906E is a good match for what we want - it is simple,
cheap, and claims to be able to be a bridge.

Can anyone confirm whether this is (likely to) work, or am I missing
something obvious here? Is anyone using one of these things to talk
to Demon in a configuration anything like ours?

Thanks

--tim