Addition...
Just been on the BT support forums. There should soon be an update that makes the vision box use the standard, broadcast freeview EPG.
In theory this should allow people to record without being on a vison enabled account (standard BT BB or even a different ISP), but this is not guaranteed. Currently scheduled recordings are stored "off-box", on a scheduling server maintained by BT. I'm sure BT would argue that this would be for wake-on-LAN should the box be in stand by mode, or as a back-up feature, but the vision box does not need an always on connection - i.e. as long as you connect every few days to update the EPG, you can free up that ethernet port on the router/hum hub.
Worth pointing out that, at least in the case of existing boxes, the update will be delivered via the net, for which you'll need access to a vision enabled line anyway.
However I'll keep an eye on developments surrounding the vision box.