I have mine at 425 yrds.
I usually lvl b/n 5-8k. Alt does not matter as much with it, speed is most important thing...keep it up and alt just does not matter much. SA is also very important if you are flying it "lower"...but once again, as long as speed is up, you should be safe.
I will dump a notch or two of flaps if I know my prey and I are alone...dont be to scared to use a notch to help you over the top, so to speak.