We do 50/50 with my children and my partner's children (my step children)both in different ways.
My step children have a pattern/rota which means they spend a few days at each home at a time, they never go more than 5 days without seeing the other parent, maximum.
My children are here alternate weeks, so 7 days at a time not seeing the other parent.
Week on week off is heartbreaking and although children are flexible and most will get used to it I honestly regret ever agreeing to it and wish we had a different pattern for alternate weeks. Lonecatwithkitten's pattern sounds very good though!
However, if things are amicable there is nothing stopping you seeing your children for a few hours on their week with their dad and vice versa is there?
Also, what about any hobbies / sports they have during the week - are you both living close enough together to both be able to achieve those on "your" weeks or are the children old enough to sort themselves getting to football club etc?
As for benefits, well that's a possible problem.
If residency is 50/50 then either parent can claim Child Benefit and either parent can claim Tax Credits. If things aren't friendly your ex could put a claim in for both and try and take them off you. If you have two children could you agree to 50/50 residency and each claim CB and Tax Credits for one child?
A parent does not need to be in receipt of Child Benefit to claim tax credits though.
However, the parent in recepit of Child benefit, could, if they wanted, go through the CSA and claim child maintenance even with 50/50 residency.