This sounds like the perfect hack for me, as I have just moved my vBulletin (that uses roughly 30 GB/month) from my primary server to my secondary one (see signature). My primary server allows 400 GB of transfer per month for a set fee (and I'm not even using 300 GB right now), while my secondary only allows 40 GB per month.
Anyway...my question is: How much bandwidth could/would I save through this? What has it done for your boards? Does attachments really account for a lot of bandwidth usage? Thanks.