The answer is that it depends on the wheel. I've had a LOT of 27 inch wheels come through over the years and a good percentage of them are moderately heavy. On the other hand, I've also had some nicer, well built wheels with nice hubs and lighter rims. Those I've held on to for future builds, or used them when the opportunity presented itself. It's also not fair to compare relatively modern wheels made from relatively modern and substantially lighter material to older, steel stuff. Did the 27s have the same number of spokes, by the way? I'm just saying it's difficult to compare apples to oranges.