
I quite agree about using older animals for breeding.
Ideally if one of the pair s young you want to sue an older mate so that you have that desirable extra info for at least half the equation.
With a youngish maiden bitch I think it always a good idea to use an older male, as it's no big deal should she miss.
With an older bitch though a young (I don't mean very young, but a male in his reproductive prime of 3 - 5 years) is a better bet though.
A lot will depend on late onset health issues within a breed, or in some breeds poor longevity.