I completely agree with 50/50 care, from a young age, this country is totally skewed in that it has gone from fathers keeping the children, to mothers doing it (in the main I do know a few male RPs).
If I was to split from DH, I would share custody, and I am an extended breast feeder, I firmly believe that the role of the working parent is being down valued in the UK, my husband is an equal parent to me, I feel he makes more sacrifices than I do, by working to provide for us.
I don't feel that being at home with the children is a sacrifice - I prefer being at home with them to being in work, I was actually the higher earner so it would make more sense for DH to have stayed home, but I missed them so much.
I have seen so many threads where the children are deemed better off with mum, simply because she has, up until a point, been the main carer, where the mans contribution means nothing, and I have seen that in RL too.
I think more men and women would leave unhappy relationships if childcare was shared, but it would take a massive cultural and legal shift for that to happen in this country.