As a green organizer my staff and I have found that with out a doubt, when we are brought in by a realator and our services are used by the selling home owner, the house sells MUCH faster. To date the last 7 homes My Divine Concierge has de-cluttered has sold at asking price or higher in 30 days or less. Our best sale was 23 hours for cash.
The trick you see is to make the home owner aware of how by getting rid of 20-30-40 or even 50 years of clutter makes their home so much more attractive for the buyer to see how they could live there. We are able to get home owners to part with their belongings because we are green and everything they get rid of is either donated to a charity or recycled. That make many people feel so much better about putting their home on a "diet".
In the end I highly reccommend that not just stagger be brought in but also a organizer who can really thin out the home and make it look really sharp for sale.