We use Q fuses in one of our more rural service territories. They use them on the 34 Kv URD and I think some transformers. We also use them on our 34 Kv Cap Banks. You're right about the weight. Those things will knock you simple if you don't get it seated right.
Speaking of fuses, how about those SME fuses? The kind with the string attached. You screw the fuse into a spring cap, then drop the fuse with string attached thru the fuse tube. Once it's out of the other end, you pull the string until it locks into place, then cut the string off. It's always funny watching the newbies trying to figure out how they get put together.