I have not seen it mentioned yet but the most important point of this tower would be that it would be the tallest tower west of Van Ness. At 299', Cathedral Hill Tower is currently the "tallest in the west:"
At 400' this would be a quarter taller than that. It would be 50' taller than Fox Plaza and obfuscate it when viewing from the west (a huge plus in my book!)
I know that Post St. tower was planned at 407', but I haven't heard news on that one in years. Are the plans still active?