Depending on your budget and location, I think a Bike Friday Tikit might work. They're not super-light, but you can get them with as many gears as you like, they're rollable (although not as easily as a Brommie). But my 14-speed Tikit climbs hills amazingly well. The down side is the expense and the size - they're large when folded. But the fold is similar to what you're used to. Get the hyperfold model and these bikes fold in maybe a couple of seconds.

Here's mine: