I'd be skeptical of a single demo. Windows 7 really benefits from more than 1GB of RAM.
I think the part of the equation people are not seeing is the fact the solid state storage that is used as a swap file. I have tried numerous times to beachball my 13" 1.8/2/256 model and with 60 safari tabs, youtube playing, iMovie playing, iPhoto, iWork's all open, iTunes playing a podcast.. it simply doesn't bog down. The damn thing is freaky how well it continues to multitask when the activity monitor shows less than 10mb of free ram.
Watching the activity monitor on disk usage it would appear to me that it's using 6gig eSATA connector vs a 3gig eSATA controller.
Bottom line until I can beachball or stall this thing out I'm not going to bother upgrading the ram. In a year or two when they bump the CPU or GPU I'll upgrade anyhow. IMO the CPU has once again become the bottleneck on the MBA, not the Ram or SS storage.