Parking Management Co's

Does anyone here live in a development where there's a parking management company.
The small estate where I live (Edinburgh) has residents parking and over the years it's got that busy (through multiple car ownership) that some residents can't get parked in the evening. The surrounding area is double yellow so on-street parking isn't readily available.
The factor (who only manages half the residents parking area) is considering bringing in a Management co at the residents expense.
I'm just wondering if anyone has experience as to how much that might cost (per resident/or year) and if they actually make a difference.
I'm sure there's small areas around Leith and at Clair Rd in particular that have managed parking but I don't see it making much of a difference?