I guess I'll feed you.
I did ask about a 17 this morning when he said he wanted to talk to the store to find out why in the world they offered me a machine that was less than that of 'like for like'. He said he wasn't sure if he could do that, and I mentioned that I would happily pay the difference between whatever machine we could get sorted out as a base point replacement and the 17.
He called me later in the afternoon saying I could get the high end 15, which I was happy to hear, and then enquired again about possibly doing a paid upgrade on/from that as the new (and proper) replacement machine, but he said I couldn't do any type of paid upgrades (not sure why). So, I tried, but couldn't do it so there's really nothing to do but be happy with the fact that the machine they are giving me has all other features of my current one sans EC; in all other areas, it is equal or better. I'll have to look into EC workarounds, as I've never thought about alternatives and I'll have to see what I can come up with and go from there.
My original upgrade plan was to go from my C2D to a Sandy Bridge/USB 3.0 machine next winter when the AppleCare expired which would be a huge upgrade, but I've got a lot better machine than my C2D coming now so we will see how that pans out; may keep this one well into and beyond Sandy Bridge if it proves to be a good machine. But who knows, I may be compelled to jump into a Sandy Bridge machine a year from now if the offer is just that good, or if in time I can't find a proper workaround for lacking an EC slot. But for now, I'll take the machine, look for workarounds, and otherwise enjoy it and be glad I got a brand new high end computer for exactly $0.