I disagree the toss height should equal the ball strike height. I think it's personal, and some great servers toss it 6' higher than their strikepoints.
Very few servers toss the height of their strikepoint.
I don't believe hitting your biggest first serves tire you out, unless you're injured, debilitated, or completely out of shape. Nobody good swings full out for first flat serves anyways. They'd like to get in a few too.
Guys without big fast first serves tend to underplay it's usage.
Those with huge first serves alway first and foremost USE IT.