Come on, SGB it's "Mumsnet - By parents, for parents" remember? It's not "Mumsnet - always assume men are wankers or fuck off".
OP yes there are a load of horror stories about child custody decisions. Some are true, some are not, most only tell one side of the story.
It does seem clear that in the majority of cases the only way that a father will get custody is if he can demonstrate the mother is unequivocally unfit. The opposite is almost never the case. And the societal norm where it is the father who goes out to work and the mother who doesn't (or only works part-time) also helps ensure that fathers will lose custody in the event of a relationship break-down.
If it does get to court and the court makes a sole residency order, then the non-resident parent not only sees the children infrequently but also loses many of the rights to involvement in important decisions that the Parental Responsibility legislation gave.
Sadly, groups like Fathers 4 Justice have done fathers no real favours. While their stunts have raised the profile of the issue they've also lost a lot of general sympathy by acting like idiots. And not all of the members are particularly pleasant characters.
It also has to be said that many fathers have given fatherhood a bad name, too. It's not easy to stand up and be heard as wanting more equality in child residency decisions when so many fathers disappear off into the distance and are never heard of again.
Families Need Fathers run a much more inclusive and legitimate campaign but they're also tarred with the same brush as F4J which is a real shame.
The good news is that, in the UK at least, courts are starting to be more willing to make shared residency orders than they used to be. A shared res order doesn't necessarily mean that the child(ren) will necessarily spend a strict 50% of their time with either parent but at least it's redressing the balance a bit.