I already have an older boy playing for Marple Athletic. It is an excellent club, well run and organised and I'd back up everything that Lee has been saying.
I also have a 6 year old who has been training with Footy4Kidz. As soon as I realised that the team they are now setting up is not actually Marple Athletic (and frankly they have not made this clear at all) the decision was easy and my youngest will only be going to Marple Athletic from now on. Marple Athletic are not trying to undercut anyone as they are not in business to make money.