Cabasilas,
I think that Jesus makes it clear how he wants us to address God when he TELLS us to pary to "Our Father".
Its defines the personal relationship we are to have with God, even if we knew God's name and how to pronunce it ( we don't really, we can speculate) it would be far more impoersonal to say it than to follow Jesus's instructions to call him as Our Father, this is what we are asked/told to do.
Should be good enough for us, no?