I tried to replace a set of if a < b {} else ... with an Ordering and the result wasn't so nice.

if a <= b {}
else {}

Can be replaced with:

match a.cmp(&b) {
    Ordering::Less => {},
    Ordering::Equal => {},
    _ => {},
}

match a.cmp(&b) {
    Ordering::Less | Ordering::Equal => {},
    _ => {},
}

But this would be nicer:

match a.cmp(&b) {
    Ordering::LessEq => {},
    _ => {},

I'm not sure how important this is though. a <= b reads so much nicer. I'm not sure where Ordering has a really strong usecase.