Replicate a big, dense Windows volume over a WAN -- too big for DFS-R

1.5 TB would take 30 minutes with http://www.exdupe.com/ :p

... given that your disks are fast enough (exdupe is so fast that it's IO bound, not CPU bound).

And I havn't reached any limits on file count yet. Had millions too.

Edit: Ah, you need a partition/sector based backup and not file system level? It can't do that... Maybe http:// www . drivesnapshot.de/en/ is worth a shot (had to add spaces because of spam protection). Does diff backups and shadow volume copy too (no reboot).

Check out Shadowprotect. It's not continuous, but it can be set to do an incremental every 15 minutes. It's pretty awesome software. Add on the ImageManager enterprise portion and it also gives you some great replication abilities for offsite backups.

I've had great luck with Doubletake, despite the price. Their "move" product might fit the budget though...

See my answer to a similar question here.