The steel fork I made for
my wife's Davidson road bike in about '89 weighed 450g, just under 1.0 lb. That was for 700c wheels, small frame (short steerer). I know it isn't the lightest though, because then later I made a still-lighter fork for a smaller rider, probably 650c wheels (I forget). That one used 7/8" chainstays as forkblades. Don't remember the weight but it was lighter. Bob Freeman of Elliott Bay Bicycles in Seattle sold it, so he may know what the fork weighed -- but I doubt it. I expect we'll never know that number.
I don't know anything about how well the lighter one rode or how long it lasted, but Laurie says that 450g fork rode great ("best ever") -- and she had her share of top-notch lightweight bikes to compare it with. She won medals at Districts and raced at Nationals, and always paid attention to bike handling. She rode it for over 15 years before the bike was retired. I don't know her mileage but it was more than I was riding! She tended to ride hard; her friends were racers and ex-racers who still liked to hammer. Rider weight about 120 lb. The fork is still fine, can still be ridden, but it doesn't fit her anymore due to too short a steerer. She's over 70 now and can't bend down so low for the bars, so she likes a much taller steerer. But I'd say the fork proved itself reliable.
Mark B