[c-nsp] DSL Aggregation equipment and sizing questions/recommendations?

[P C]

I need to terminate 2,000 DSL circuits delievered to me from a telco over a
an ATM DS3.  I was hoping someone here could offer some equipment
recommendations that they feel are suitable for terminating this traffic, as
I'm having trouble understanding all the IDB and PVC limits offered by the
different platforms.  I anticipate I'll be running PPPoX and terminating all
the sessions including PPP on a single router, but I am open to options.

I know the following will occur:
* Each site will have a routable IP block
* This network will have to support extremely low-bitrate multicast traffic.
* Each site will be running PIM-SM.
* This deployment will have an unusual traffic loading.  I expect unicast
traffic to never exceed 5mbps for all sites combined.  If multicast traffic
is included, I always expect the loading to remain under 15 megabit, even
after it is replicated out down each PVC.
* This is not an ISP scenario, nor will it carry any internet traffic.

I was thinking something in the 7200 product lines or the ASR series
(probably no way a 3900 can handle the PVCS, even if the traffic is ok?) but
ultimately I would like something that would both keep costs down, and
likely to remain on vendor support for the better part of a decade.

I'd appreciate any suggestions.

Thanks,
Paul