How Grand Central Might Be Useful To Me

I have been thinking about the whole "I don't want to change numbers" thing and how it relates to Grand Central. 

If Grand Central actually supported both incoming calls via SIP along with outgoing calls via SIP, Grand Central might start being interesting to me. I could then direct my landline to Grand Central via PhoneGnome, which could then be redirected elsewhere. Futhermore, if I could have a SIP URL as one of my numbers to try, it'd be insanely useful.

Like Ken Camp says, though, this starts looking like needless backhaul. But at least with SIP URLs, the cost of that backhaul is nearly zero.