I've been on the lookout for one of these. Should be pretty light? Does it sound like a featherweight? I always thought the aluminum-bodied machines sound a little clattery: not a bad thing, but not as soothing/sophisticated as the sound all that dense cast iron produces, as a rule.
The most laughable of the "lightweights" are the magnesium-bodied White "portables" which outweigh your average Hyundai. These sound like any White Rotary: rumbly, grumbly, unstoppable except when that goofy drive mechanism cops a mood. They're quirky enough that I like them, but I don't love them. They'e the machine I give away to relatives, etc. They're cheap, and once you get that rubber snubby business squared away, they're liable to run forever: just prop that thing away from the wheel when not in use so that it doesn't develop a dent, and scrub a little sandpaper on it from time to time. (The aftermarket snubbies stink, by the way: plasticky, slick, weak. (Sorta like politicians, come to think of it.)