Not really. There's roughly twice as much ammonium in the F-7, but the only thing it does is assist in mobilizing the silver ions. It's almost a catalyst. so it doesn't matter (much) how much there is, as long as it's sufficient.
I have no idea how much is sufficient.
My own recipe uses chloride, since I have an idea that the chloride will help in dissolving silver iodide. But I could be completely wrong. At least it works...